ABC's Z. Byron Wolf ( @zbyronwolf) reports:

Top GOP Senator Tells Jon Karl - 'If Romney Loses Michigan, We Need a New Candidate' http://abcn.ws/xgLCiw

But GOP Savior Would Require Brokered Convention, according to Elizabeth Hartfield's Math - http://abcn.ws/zqPysg

Feds Arrest Would-Be Bomber Near Capitol - http://abcn.ws/zuwwcv

Holder Won't Defend DOMA Challenge Brought by Military Members - http://abcn.ws/ydD4Hg

Gay Marriage and Abortion Trap VP Picks - Matt Negrin on how potential Veep picks Chris Christie and Bob McDonnell are facing opposing but equally bedeviling social issue quandaries - http://abcn.ws/x3zdb7

DeWine's Mulligan - They swept into the U.S. Senate together in the 1994 Republican revolution, when Republicans took control. They lost together in 2006 when Republicans lost control. And today former Sen. Mike DeWine took an endorsement mulligan, snatched back his preference from Mitt Romney and decided to stand instead with Rick Santorum. According to DeWine, Romney has shown an "astounding inability to provide voters with a rationale to support him." As for Santorum, "People like him - he's human!" DeWine said. http://abcn.ws/yK7T2v

Romney Warns of Voting Against Santorum, Still Uses Govt. Spending Argument - http://abcn.ws/yzJjUO

Congress Sends Payroll Tax Cut Extension to Obama - http://abcn.ws/zRG3Z1

More Contraception / Religion Hearing Blowback - http://abcn.ws/AxjMYs

AF 1 Returns to the Nest for Campaign Event - http://abcn.ws/wAcxnn

Midwest Hearts Santorum, argues Matt Jaffe - "Thus far, Santorum has simply owned the Midwest. He won Iowa. He won Minnesota. He won Missouri. The region, laden with social conservative voters, has sided time and time again with the former Pennsylvania senator, the most outspoken candidate on issues such as abortion." http://abcn.ws/xL5d4R

Bubble Primary Part II - More from Jaffe - A Bubble Primary: a race in which candidates' values become artificially high before inevitably deflating back to their intrinsic values. http://abcn.ws/zx1kxE

Calendar Check - Chris Good Says Thanks to Texas and Pennsylvania, GOP Race Could Last Nearly Forever -   http://abcn.ws/AaeHiD

Fact Check - Rick Santorum's Record With Labor Unions - Not Buddy Buddy - http://abcn.ws/wrHkgj

No Boss - Bruce Springsteen Sitting Out 2012 but Backs Obama - http://abcn.ws/wu6nI5

Maine's Caucus Confusion: One County Might Be Included After Saturday - http://abcn.ws/xUv8Hi