Casey's split with Obama on the issue makes sense politically. His last name is a rallying cry for pro-life Democrats, thanks to his father's outspoken opposition to abortion rights. And Pennsylvania is one of the few states where the party's solidly working-class base could break with the president on the decision. According to exit polls from the 2008 presidential election, 32 percent of Pennsylvania voters identified themselves as Catholics. Facing a potentially tough reelection fight, Casey can't afford to alienate working-class voters who might be offended by the HHS mandate. It's important to note that Vice President Joe Biden, a Scranton native who regularly talks up his working-class Catholic background, has been notably silent about the decision. A decent number of Democratic voters in areas like Scranton and Pittsburgh will have major problems with the president's decision. Casey's potential Republican opponents regularly link the senator to Obama and his lagging approval rating in the state. In a Quinnipiac poll conducted in December, 43 percent of registered voters in the state approved of Obama's job performance, while 52 percent disapproved. When Obama visited Scranton, Casey's hometown, at the end of November, Casey did not attend the speech. Casey said he stayed in D.C. to vote on a defense appropriations bill, but others suggested he avoided appearing alongside Obama. While his opponents claim he is one of Obama's most loyal votes in the Senate, Casey can now point to the controversy over the mandate as an area of disagreement with the White House. Rep. Joe Donnelly, D-Ind.: Like Casey, Donnelly is a Catholic who opposes abortion rights. But, as the NRSC pointed out in a release on Wednesday, Donnelly hasn't made a public statement on the religious exemption controversy. Donnelly's staff did not respond to Hotline on Call's requests for comment. Donnelly's district is home to the University of Notre Dame, whose president, Father John Jenkins, has already expressed his displeasure with the administration's decision. Donnelly has both an undergraduate and law degree from Notre Dame, and there could be some pressure at home to come out against the mandate. Such a move could also make sense politically. Donnelly doesn't face any opposition in the Democratic primary, making it unlikely that he'll face significant criticism from his left if he breaks with the White House on this issue. He faces an uphill challenge in the general election, especially if Sen. Richard Lugar, R-Ind., wins the primary, and he needs to make inroads with moderate and independent voters. Sen. Claire McCaskill, D-Mo: McCaskill, who is in favor of abortion rights, had this to say to the Kansas City Star earlier this week: "This is an emotional, difficult subject. It's always one that's difficult. But if you really believe that reducing abortions are important in this country, which I do, then it doesn't work to keep putting up barriers to women getting birth control." "As someone who believes very much that we should be preventing abortions, I think we should try very hard to give women universal access to birth control without going into their pockets," she also told reporters this week. Politically, McCaskill's positioning makes sense. If she were to take a stand against the president on the issue, she would risk alienating her Democratic base, whom she needs to turn out in strong numbers come the fall. It's also consistent with McCaskill's overall strategy, which has been to not run away from the president at every single opportunity. Rep. Tammy Baldwin, D-Wis. It shouldn't be much of a surprise that Baldwin, a stalwart social liberal in the House who has received strong support from EMILY's List, has come out in favor of the president's decision. "Congress can impose no laws on a church. Nevertheless every woman, regardless of her faith, should have access to full insurance coverage and preventive care. For example, a nurse who works at a religiously affiliated hospital should have access to the same coverage as a nurse who works for a public one." But Wisconsin is a state with a significant Catholic population. Many of these working-class voters will be key swing voters in her Senate campaign - and rhetoric like this could potentially alienate them in a general, if the issue still has legs by then. Sen. Joe Manchin, D-W.Va.: During his time as senator -- and even before he took office -- Manchin has been no stranger to speaking out against administration policies and positions. Who can forget the 2010 TV ad in which the now-former governor shot the camp and trade bill? Manchin called the mandate "un-American" in a letter he sent the president last week, the AP reported. Manchin and his political doppelganger, Democratic Gov. Earl Ray Tomblin have won their respective elections by keeping Obama at arm's length -- something that will be especially important for both this year, with the president atop the ticket.