By MICHAEL FALCONE ( @michaelpfalcone )

NOTABLES

• AN ONLINE TRAFFIC JAM: As Obamacare's first sign-up season came to a close, the website was jammed with traffic late into the night, ABC's DEVIN DWYER reports. The White House says Monday was a record-breaking day of turnout online, at enrollment centers and over the phone: more than 3 million visits to HealthCare.gov and more than 1 million calls to the call center as of 8 p.m. yesterday. All indications are that the Obama administration is closing in on 7 million sign-ups since Oct. 1. People who tried and couldn't get through the process yesterday can come back today and start fresh or continue their applications.

• AS FOR THE WEBSITE ITSELF: It got a midnight makeover. Here's what happened, according to a statement from Centers for Medicare and Medicaid Services: "Beginning at 12am EST HealthCare.gov's marketplace application and enrollment system will go offline for a few hours to allow the tech team to make the changes necessary to reflect the actions consumers can take now that the annual open enrollment window has ended. As usual, some of the federal data services will also undergo their routine nightly maintenance during this time period. We expect the site and all services to resume early Tuesday morning."

THE ROUNDTABLE

ABC's RICK KLEIN: Thank Zach Galifianakis, or Alonzo Mourning, or just thank the base for coming home. Whatever the reason, Democrats can draw a rare dose of optimism out of the new ABC News/Washington Post poll, which shows Obamacare nosing above water, with 49 percent support and 48 percent opposition. The mini-surge is driven by younger and lower-income adults, as well as minorities - even a softening of opposition among some conservatives. It suggests that perceptions of Obamacare may not be quite as stubborn as the political class has long assumed. But turning Obamacare into less of a loser, as opposed to a winner - that's a different challenge entirely. The Democrats' biggest problems in 2014 will center on turnout, in finding a way for them to be as motivated to vote as Republicans say they are now. Neutralizing Obamacare would be a start, but only that.

BUZZ

AMERICANS FOR PROSPERITY UNLEASHES ANOTHER ATTACK ON MARK PRYOR. Americans for Prosperity, the conservative group financially backed by the Koch Brothers, is targeting Sen. Mark Pryor, D-Ark., with a new ad highlighting his position on Obamacare, increasing its ad spending in the Arkansas Senate race to over $1.8 million, ABC's ARLETTE SAENZ and MICHAEL FALCONE report. The minute long ad features a man named Jerry, who runs a trucking business and is frustrated with the uncertainty of his health care coverage due to the Affordable Care Act. "It's like living in a haze. You don't know whether you're going to have insurance or whether you're going to be able to afford your insurance. It was taken away from us, or it was given back to us, or it was taken - we don't know what it's been now," Jerry says in the ad. "I think the American people are tired of this constant angst, this constant crisis, they want certainty in their lives." The commercial will run across Arkansas starting Tuesday for three weeks backed up by $540,000 ad buy. http://abcn.ws/1i9Cvvv

OBAMACARE ADS WIN MILLENNIALS' APPLAUSE, BUT DID THEY ENROLL? The Obamacare team has used Hollywood celebrities, star athletes, animals, online games and memes to entice young people to the state and federal healthcare exchanges before yesterday's midnight deadline. They even put the president on Zach Galifianakis' snarky web series "Between Two Ferns." The marketing strategy may be paying off, ABC's ERIN DOOLEY notes. According to a poll released by Pew Research Center for People & the Press earlier this month, 50 percent of young adults, age 18 to 29, now say they "approve" of Obamacare. Compare that to a similar survey taken three months ago. Back in December, just 41 percent of those in the 18-29 demographic said they approved of the president's signature healthcare law. The number of 18- to 29- year-olds who disapprove of the Affordable Care Act has fallen by 7 percentage points, from 54 percent in December to 47 percent last week. http://abcn.ws/1lyBFxK

CATERPILLAR INC. AVOIDED $2.4 BILLION IN U.S. TAXES, SENATE REPORT SAYS. Caterpillar Inc., a U.S. manufacturer of construction equipment, has avoided paying $2.4 billion in taxes by shifting billions of dollars in profits to a wholly owned Swiss affiliate, a new report from Sen. Carl Levin, chairman of the U.S. Senate Permanent Subcommittee on Investigation, says, according to ABC's ARLETTE SAENZ. The report, which was compiled by the subcommittee's majority staff, concluded that Caterpillar shifted $8 billion in profits from its parts manufacturing division in the U.S. to Switzerland. Caterpillar negotiated a tax rate of 4 percent to 6 percent with Switzerland, whose federal statutory tax rate is typically 8.5 percent. "In the fantasyland of international tax, Caterpillar waved a magic wand to make billions of dollars in U.S. taxes disappear," Levin said yesterday. "This is a prime example of a tax avoided strategy that cost the U.S. Treasury billions of dollars." http://abcn.ws/1mFRWBg

ROSIE THE RIVETERS TAKE WHITE HOUSE BY STORM, GET HUGS FROM JOE BIDEN. The original six "Rosie the Riveters" who worked in a shipyard during World War II traveled to Washington yesterday in hopes of fulfilling one of their dreams: getting a hug from Joe Biden, ABC's ALEXANDRA DUKAKIS notes. "Oh my gosh, it was wonderful. I had written a letter to the vice president and in it I said my dream would be to have my picture taken with the two of them in the Oval Office, and I got it," gushed 91-year-old Phyllis Gould, of California, whose letter prompted the women's meeting at the White House. In her letter, Gould also expressed her desire to get a hug from the vice president, another dream that came true yesterday. "He came bursting out of a room and grabbed me and … then he hugged everyone," Gould said. One Riveter said President Obama "kissed all of us" during his meeting with the women. "And Biden did too!" another chimed in. The Riveters worked as welders, electricians and draftsman at the Kaiser Shipyard in Richmond, Calif., during World War II. http://abcn.ws/1gVkDba

IN CASE YOU MISSED IT

CLIMATE CHANGE: IT'S NOT THE FUTURE: IT'S HERE NOW. Lower Manhattan underwater from rising seas during hurricane Sandy; wildfires - many more of them like the one in Colorado; droughts in the American West; and wicked hurricanes and typhoons like Haiyan, the one in the Philippines last year: All these, according to a new report from the UN's climate panel released yesterday, are signs of the impact of climate change, ABC's JIM AVILA and SERENA MARSHALL note. "We are experiencing the impact here and now; Global warming is occurring," Noah Diffenbaugh, associate professor Stanford University and coauthor of the report told ABC News. "The impact of global warming is already being felt. It is being felt across the continents; they are being felt in the ocean. This is not just about the risk of climate change a century from now but it's really about managing the risk of the current climate." And while global warming is easiest to see at the poles, with ice caps being drastically reduced over the past 10 years, this new report by a United Nations sanctioned science panel says there is no more debate: Global warming is real, here now, wreaking havoc worldwide and caused by humans. The first sentence of the report lays it pretty simply: "Human interference with the climate system is occurring, and climate change poses risks for human and natural systems." http://abcn.ws/1s0cnKl

WHO'S TWEETING?

@Simas44: Pretty close to a perfect day! #RedSox at the White House and huge close to #ACA enrollment -> peace of mind to millions. #MillionsCovered

@phoebedoris: We need a new term for what's happening on DC roads. Pot tunnels? Pot caverns? Pot holes doesn't really do justice …

@mshields007: The party of the left gets its proper color RT @Reince: Very exciting news on the future of the party: http://bit.ly/QAdMJI

?@CrowleyTIME: My story on Jonathan Pollard explains why Bill Clinton nearly released him in 1998-and what stopped him: http://time.com/44281/jonathan-pollard-israel-obama/ …

@ehuetteman: It's primary day in DC, which is effectively election day in a city where about 76 percent of voters are Democrats.