Image credit: Douglas Graham/CQ Roll Call/Getty Images

By MICHAEL FALCONE ( @michaelpfalcone )

NOTABLES

• 'POND SCUM': That, according to ABC's JEFF ZELENY, is the expression Sen. Jeff Flake, Republican of Arizona, used to characterize how some critics viewed him after he voted against expanding background checks two week ago during the gun control debate in Congress. In a posting yesterday on his Facebook page, Flake conceded that his "poll numbers have indeed taken a southerly turn." The gun control debate is quiet in Washington, but it is only getting started at home for some senators, particularly those who were on the fence but opposed a bipartisan compromise on expanding background checks for people who buy weapons at gun shows and on the internet. http://abcn.ws/Zkn0XP

• NEWTOWN GOES TO THE GRANITE STATE: Zeleny notes that Sen. Kelly Ayotte, Republican of New Hampshire, faced a confrontational exchange during a town meeting yesterday in Warren, N.H. The daughter of the principal killed at Sandy Hook Elementary School challenged Ayotte on her vote against the background check measure, according to the Political Scoop blog on WMUR.com. "You had mentioned that date you voted, owners of gun stores that the expanded background checks would harm," said Erica Lafferty, whose mother was killed in the Newtown, Conn., shooting four months ago. "I'm just wondering why the burden in of my mother being gunned down in the halls of her elementary school isn't as important." Ayotte has been besieged with advertising from both sides of the gun debate. She apologized to Lafferty for her loss, but renewed her objections to the background check bill, saying she did not believe it would have prevented the mass shooting in Newtown. http://abcn.ws/Zkn0XP

• U.S. EXPANDING SUPPORT TO SYRIAN REBELS: President Obama has directed his national security team to identify ways to significantly ramp up U.S. support of the opposition forces battling Syrian President Bashar al-Assad, ABC's JONATHAN KARL reports. Among the options under consideration are supplying arms to rebel forces, although no decision on that has been made. The first step will likely be a dramatic expansion of non-lethal aid to opposition fighters. "The items to be supplied will be decided after consultations with the Supreme Military Command," National Security Council Spokesperson Caitlin Hayden tells ABC News. "Additional communications equipment, armor, night vision goggles and vehicles are among the items being discussed." Hayden also suggested aid to the rebels could go beyond such non-lethal assistance.

THE ROUNDTABLE

ABC's RICK KLEIN: It's already become trite to reference Scott Brown in stories of why impossible upsets may just be possible in special Senate elections. That's especially true in Massachusetts (or, maybe soon, New Hampshire). But you'd be hard-pressed to cast a more nationally compelling candidate than Gabriel Gomez, the new GOP Senate nominee in Massachusetts: Son of Colombian immigrants, Naval Academy, Navy SEAL, Harvard MBA, successful businessman. There's no questioning Rep. Ed Markey's Democratic credentials or legislative record. To continue the too-well-worn comparisons, he's no Martha Coakley. But Markey has hardly had to campaign for decades, and hasn't run statewide since he briefly sought this same Senate seat back in … 1984. This race will be Markey's to lose until Gomez can prove he can compete. Democrats won't let this one slip away without a fight. Republicans, though, overwhelmingly chose the candidate who's bound to make Democrats sweat it out.

ABC's SHUSHANNAH WALSHE: New Jersey Gov. Chris Christie is out with his first television ad of his gubernatorial re-election campaign. Sixty seconds long, the ad will begin running in the major media markets of New York City and Philadelphia Wednesday. Christie's campaign announced that the buy will be large - $1.2 million. Although the ad doesn't directly mention Superstorm Sandy, which hit the state six months ago, there are images throughout. "Working with Democrats and Republicans, believing as long as you stick to your principals compromise isn't a dirty word," the narrator says as the ad shows Christie shaking hands, greeting voters and comforting New Jersey residents after Sandy. "But the most important thing he did has little to do with numbers, statistics or even politics: He made us proud to say we're from New Jersey." The ad ends with video of Christie looking at the Seaside Heights, New Jersey skyline. Christie's opponent, Democratic State Sen. Barbara Buono, has not launched any television ads of her own yet. Christie is heavily favored in the race. The most recent Quinnipiac University poll conducted earlier this month showed Christie ahead of Buono by 32 points, 58 to 26 percent. http://abcn.ws/11XbCDs

ABC's MICHAEL FALCONE: That Mark Zuckeberg is facing liberal ire over television ads his political groups sponsored patting lawmakers on the back for opposing Obamacare and supporting expanded oil drilling should come as little surprise to the Facebook founder who is now dabbling more actively in politics than ever before. But perhaps the fact that Zuckerberg is willing to help bankroll the commercials, which are in service of his main goal - achieving comprehensive immigration reform - shouldn't be so shocking to progressive activists either. After all, Zuckerberg is something of a political man of mystery. For example, Zuckerberg and other technology leaders dined with President Obama in February 2011 and he hosted the president at a friendly town hall meeting two months later at Facebook's offices. But he also threw a fundraiser earlier this year for Gov. Chris Christie, the New Jersey Republican and potential 2016 presidential contender. According to the Wall Street Journal, Zuckerberg is registered to vote in Santa Clara County but did not state a party preference.

HAPPENING TODAY: Freedom House will release their latest report today, "Press Freedom in 2012: Middle East Volatility Amid Global Decline." The report found that In 2012, the percentage of people worldwide who enjoy a free media environment fell to its lowest point in more than a decade. Freedom House is convening a discussion today at the Newseum in Washington, DC moderated by ABC's REENA NINAN. Panelists include: Karin Deutsch Karlekar, PhD, Project Director, Freedom of the Press; Jackie Northam, Foreign Correspondent, National Public Radio; and Adel Iskandar, PhD, Adjunct Professor at Georgetown University and media scholar. More information: http://bit.ly/17vwaGl

BUZZ

MARK ZUCKERBERG'S POLITICAL STATUS: IT'S COMPLICATED. Less than three weeks after Mark Zuckerberg officially launched his pro-immigration reform group, the billionaire technology mogul seems to be experiencing the Facebook equivalent of a liberal de-friending. ABC's MICHAEL FALCONE reports that progressive activists have been voicing their disapproval after two Zuckerberg-backed groups unveiled television ads last week praising lawmakers for opposing Obamacare and supporting an expansion of the Keystone oil pipeline and drilling in the Arctic National Wildlife Refuge. The ads are meant to provide political cover for three senators - Lindsey Graham, Republican of South Carolina; Marco Rubio, Republican of Florida; and Mark Begich, Democrat of Alaska - to cast politically risky votes in favor of immigration reform. Those television commercials led the Sierra Club to post a message on its Facebook page on Monday urging Zuckerberg to "re-think his priorities." At least two other groups - CREDO Action, the liberal arm of CREDO Mobile, a cellular phone company, and the "climate safety" organization, 350.org - publicly lashed out at Zuckerberg this week. A CREDO spokeswoman said 18,5000 people signed an online petition condemning the ads and, along with 350.org, they are planning a protest outside Facebook headquarters in California today. http://abcn.ws/YmcmEX

MORE FROM THE SIERRA CLUB: "Just last week, the Sierra Club announced our support for a path to citizenship for undocumented immigrants - so we know how important immigration reform is to the future of our country," Michael Brune, the group's executive director, said in a statement to ABC News. "The way to achieve reform, however, isn't by pushing dirty fuel schemes that threaten our future and our families. Mark Zuckerberg has made comments in the past recognizing that we need to pursue a clean energy future, and there is no reason he needs to trade those principles for a few political points." http://abcn.ws/YmcmEX

ED MARKEY, GABRIEL GOMEZ WIN SENATE PRIMARIES IN MASSACHUSETTS. Democratic U.S. Rep. Ed Markey, D-Mass., and Republican businessman Gabriel Gomez were the winners of yesterday;s primary for the special election to fill the U.S. Senate seat vacated when John Kerry became Secretary of State, ABC's SHUSHANNAH WALSHE reports. Markey, a House member since 1976, bested U.S. Rep Stephen Lynch, D-Mass., and Gomez beat out former acting ATF director and former U.S. Attorney Michael Sullivan, as well as state legislator and former general counsel to Mitt Romney, Dan Winslow, the Associated Press determined. Markey and Gomez will face off in the general election on June 25. Markey was heavily favored to beat Lynch and had the backing of establishment Democrats in the state. "On the Democratic side, it's a decisive victory for Ed Markey and, for all intents and purposes, he was the official Democratic nominee although the party was ostensibly neutral," Tufts political science professor Jeffrey Berry told ABC News. Lynch was the more conservative Democrat and tried to appeal to more blue-collar Democratic voters, but he was also up against Markey's well-organized machine. Gomez, a Latino businessman in the state and a former Navy SEAL with a Harvard MBA, is a political newcomer, but his moderate appeal won over voters in blue Massachusetts. Although Markey will be heavily favored to win the general election, Berry said it will be a real fight despite Markey's organization. http://abcn.ws/12jZQl8

NOTED: Craig Varoga, a strategist at the pro-Democratic Senate Majority super PAC, penned a memo titled: "Gabriel Gomez Is Mitt Romney Jr." Here's an excerpt: "After barely escaping with a narrow victory over less than stellar opponents in a low turnout primary, Gabriel Gomez is now bringing his 'I am Mitt Romney Jr.' campaign to the general election. From protecting special tax breaks for billionaires at the expense of seniors and students, to surrounding himself with political insiders from Romney 2012, to talking out of both sides of his mouth, Gabriel Gomez is running a 'Mini Me' retread of Mitt Romney's epic failure of a presidential campaign. Maybe that's why Gomez's staff is a Romney reunion." Full memo: http://bit.ly/12So60y

MARK SANFORD'S DAY OF ENDORSEMENTS. On Monday night, South Carolina House candidate and the state's former governor, Mark Sanford, debated Elizabeth Colbert Busch, fending off mentions of his affair before a raucous crowd. Yesterday, the endorsements rolled in. The National Republican Congressional Committee already pulled its support for Sanford but on Tuesday Sen. Rand Paul, R-Ky., offered his backing, and the conservative group FreedomWorks followed suit. So did Larry Flynt. The noted porn king, candidate and political agitator released a sarcastic YouTube endorsement of Sanford as "America's great sex pioneer," announced a donation of a legal-maximum $2,600 to Sanford's campaign, and invited Sanford to "meet with me, man to man, for a photo opportunity and to shake my hand in gratitude for my endorsement." In the video - either falsely or earnestly - Flynt praised Sanford for exposing the "sexual hypocrisy of traditional values in America today" - and praised pro-Sanford voters for their willingness to allegedly reject those values in favor of Sanford's candidacy. http://abcn.ws/14R5L84

OBAMA ADMINISTRATION DENIES BENGHAZI WHISTLEBLOWERS BEING KEPT QUIET. More than seven months after the attack Sept. 11, 2012, on the U.S. consulate in Benghazi, Libya, the Obama administration continues to defend itself against allegations from House Republicans that the administration has not fully cooperated with Congress on the investigation into the attack, notes ABC's DANA HUGHES. On Tuesday, both President Obama and Secretary of State John Kerry addressed claims being made by House Oversight and Foreign Affairs Committee leaders that the administration is impeding the Congressional testimony of State Department and CIA employees who survived the attack. "I'm not familiar with this notion that anybody's been blocked from testifying," said the president. "What I've been very clear about from the start is that our job with respect to Benghazi has been to find out exactly what happened, to make sure that U.S. embassies, not just in the Middle East but around the world, are safe and secure and to bring those who carried it out to justice." Speaking to reporters on Tuesday, Kerry said "there's an enormous amount of misinformation out there" about Benghazi. He referenced his testimony before the House two weeks ago, when he told members that the State Department would work closely with Congress to clear up any lingering questions about the attacks so that everyone could move on and begin focusing on other pressing global issues. "I do not want to spend the next year coming up here talking about Benghazi," Kerry said. http://abcn.ws/18o9I0w

WHAT WE'RE WATCHING

YOUNG MINDS WITH BIG IDEAS: MEET THE WHIZ KIDS OF THE WHITE HOUSE SCIENCE FAIR. 10-year-old Evan Jackson had just made a touchdown in his football game, but he had to be pulled off to the sideline because he had overheated. It got him thinking, along with his brother Alec and cousin Caleb: what if there were a way to keep football players cool and hydrated without having to leave the field? The three boys-all elementary school students from McDonough, Georgia-came up with a prototype of a hydration and cooling system for football players. And along with 30 students, they were invited to present their award-winning science and engineering project to President Obama at the 3rd Annual White House Science Fair. "The idea of cool pads is shoulder pads that have an ice pack and Gatorade built in to prevent against heat exhaustion and save lives," they explain to Politics Confidential, pointing to their display set up inside the White House. "It works by using three basic features-the compression shirt, the helmet, and the shoulder pads." To hear more about these big ideas from young brains, and to judge for yourself whether President Obama or ABC's JONATHAN KARL generated more clean water, check out this episode of "Politics Confidential." http://yhoo.it/ZVEpJw

WHO'S TWEETING?

@LangerResearch: 70% support death penalty if accused Boston Bomber is convicted; 3 in 4 support federal trial: http://abcn.ws/1013xuw #poll

@BDayspring: Maureen Dowd calls Obama a Lame Duck… Says he should grab that drink with Mitch McConnell. That Maureen Dowd. Ouch. http://ow.ly/kBkzL

@andymstone: Why are House GOPers afraid to meet their constituents this recess? Let's look at just the top 4 reasons: http://youtu.be/vxPcGRNvqHw

@motherjones: What the NRA's Millions Do-And Don't-Buy http://bit.ly/12UQLSp

@politicalwire: Rep. Jack Kingston appears to be readying a GA-Sen announcement for later this week http://politicalwire.com/archives/2013/05/01/kingston_seems_to_be_readying_senate_announcement.html …