The Note's Must-Reads are a round-up of today's political headlines and stories from ABC News and the top U.S. newspapers. Posted Monday through Friday right here at www.abcnews.com

Compiled by ABC News' Carrie Halperin, Jayce Henderson and Will Cantine

BOSTON BOMBER Bloomberg's Terry Atlas & Roxana Tiron: " FBI Handling of Russia Boston Bomber Tip Draws Scrutiny" The FBI, initially lauded for its quick identification of the suspected Boston Marathon bombers, now is facing scrutiny from lawmakers about its handling of a 2011 Russian tip that might have averted the attack. The Senate and House have scheduled hearings this week, and the Republican chairman of the House Homeland Security Committee, Michael McCaul of Texas, asked the FBI and other security agencies for all documents on Tamerlan Tsarnaev, the elder of the two brothers linked to the bombing. LINK

ECONOMY The Wall Street Journal's Damian Paletta: " Obama Budget Spreads The Tax Pain" President Barack Obama's budget proposal would lead to significant tax increases on upper-income Americans, and also to moderate increases on some lower-income Americans, largely because of a new tax on tobacco products, according to an analysis by a Washington think tank. LINK

The Hill's Brendan Sasso and Bernie Becker: " Internet sales tax advances after Obama endorsement" Legislation that would empower states to tax online purchases cleared a key hurdle in the Senate on Monday after winning an enthusiastic endorsement from President Obama. Senators advanced the bill in 74-20 procedural vote on Monday evening, just one vote short of the backing it received in a test vote last month. Twenty-six Republicans joined Democrats in moving forward with the bill. LINK

ENERGY AND THE ENVIRONMENT The Los Angeles Times' Neela Banerjee: " EPA releases harsh review of Keystone XL environmental report" The Environmental Protection Agency issued a sharply critical assessment of the State Department's recent environmental impact review of the controversial Keystone XL pipeline, certain to complicate efforts to win approval for the $7-billion project. LINK

IMMIGRATION The Washington Times' Stephen Dinan" " 99.5% of illegal immigrants get approval for legal status High number raises concerns about fraud" The administration has approved 99.5 percent of applications of those who have applied for legal status under President Obama's nondeportation policy for young adults, granting legal status to more than 250,000 formerly illegal immigrants. Officials said they expect the approval rate to drop as more cases make their way through the system, as it takes longer to deny an application than to approve it. LINK

Politico's Emily Schultheis: " Immigration reform could be bonanza for Democrats" The immigration proposal pending in Congress would transform the nation's political landscape for a generation or more - pumping as many as 11 million new Hispanic voters into the electorate a decade from now in ways that, if current trends hold, would produce an electoral bonanza for Democrats and cripple Republican prospects in many states they now win easily. Beneath the philosophical debates about amnesty and border security, there are brass-tacks partisan calculations driving the thinking of lawmakers in both parties over comprehensive immigration reform, which in its current form offers a pathway to citizenship - and full voting rights - for a group of undocumented residents that roughly equals the population of Ohio, the nation's seventh-largest state. LINK

USA Today's Aamer Madhani and Alan Gomez: " Boston Bombings Loom Large In Immigration Debate" The White House on Monday pushed back against suggestions from some Republican lawmakers that last week's bombings at the Boston Marathon should slow down the conversation on an overhaul of the nation's immigration laws. Sen. Rand Paul, R-Ky., suggested on Monday that last week's bombings - which authorities suspect was carried out by two young Chechen immigrants - casts a shadow on the immigration debate. LINK

The Boston Globe's Tracy Jan and Michael Kranish: " Fallout From Bombings Threatens Immigration Measure" The fallout from the Boston Marathon bombings is threatening passage of immigration legislation, as conservative Republicans said on Capitol Hill, talk radio, and Twitter that the alleged participation of ethnic Chechen brothers shows the need for slowing down or halting the bill. LINK

GUN CONTROL The New York Times' Michael Shear and Peter Baker: " In Gun Bill Defeat, a President Who Hesitates to Twist Arms" Senator Mark Begich, Democrat of Alaska, asked President Obama's administration for a little favor last month. Send your new interior secretary this spring to discuss a long-simmering dispute over construction of a road through a wildlife refuge, Mr. Begich asked in a letter. The administration said yes. LINK

GEORGE W. BUSH ABC News' Gary Langer: " G.W. Bush Advances In Esteem Yet Still Without More Brush To Cut" After the most unpopular second term of the post-World War II era, George W. Bush has gained in public esteem as time since his presidency has passed - not that the public's ready yet to throw him bouquets. Just more than four years after he left office, with his presidential library about to open its doors, Americans divide on Bush's performance during his tumultuous eight years as president: Forty-seven percent approve while 50 percent disapprove in a new ABC News/Washington Post poll. LINK

The Washington Post's Dan Balz: " As Bush library opening puts his presidency back in the spotlight, his approval is up" George W. Bush will return to the spotlight this week for the dedication of his presidential library, an event likely to trigger fresh public debate about his eight fateful years in office. But he reemerges with a better public image than when he left Washington more than four years ago. Since then, Bush has absented himself from both policy disputes and political battles. A new Washington Post-ABC News poll suggests that the passage of time and Bush's relative invisibility have been beneficial to a chief executive who left office surrounded by controversy. LINK

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