More than a few high-profile Democrats have been walking the same line on gay marriage that President Obama walked until today: dutifully supporting the repeal of discriminatory measures like the military’s Don’t Ask, Don’t Tell Policy, and in many cases even supporting civil unions—but stopping short of an outright endorsement of marriage equality.

But these Democrats are marching without a leader, now that the president has announced a change of heart. As Richard Kim points out, since Obama stressed that he thinks states should decide the gay marriage issue, this is a step shy of endorsing full marriage equality—but it still suddenly places Obama to the left of many high-profile Democrats, many of whom are up for re-election this fall.

Twenty-two Democratic Senators support gay rights and are explicitly pushing for that plank to be added to the Democratic Party platform this summer, something that seems all the more likely now. But here’s a quick look at some others who are probably huddled with advisers as we speak, trying to figure out if they, too, should “evolve.”

Senate Majority Leader Harry Reid, D-Nevada

This is a big one. Re-elected in 2010 to what many believe could be his last term in the Senate, Reid has been a good advocate for LGBT Americans on many issues—under his leadership the Senate repealed “don’t ask, don’t tell” (DADT) and rejected Republican attempts to strip LGBT protections from the Violence Against Women Act. He’s also repeatedly voted against constitutional amendments that would define marriage as between a man and a woman.

But Reid is a member of the Mormon church, and has stated that he agrees, personally, with the church position that marriage is between and man and a woman only. With Obama, Biden and Nancy Pelosi all in favor of gay marriage, Reid stands as the highest-ranking Democratic official not to support it. 

UPDATE: Reid put out a statement reiterating his personal belief that marriage is between a man in a woman, but also endorsing Americans’ ability to enter into same-sex marriage, and adding that individual states should decide. The statement in full: "My personal belief is that marriage is between a man and a woman. But in a civil society, I believe that people should be able to marry whomever they want, and it’s no business of mine if two men or two women want to get married. The idea that allowing two loving, committed people to marry would have any impact on my life, or on my family’s life, always struck me as absurd. In talking with my children and grandchildren, it has become clear to me they take marriage equality as a given. I have no doubt that their view will carry the future. I handled a fair amount of domestic relations work when I was a practicing lawyer, and it was all governed by state law. I believe that is the proper place for this issue to be decided as well.”

Senator Bob Casey, D-Pennsylvania

The first-term Senator voted to repeal DADT and supports civil unions. But this week, after Joe Biden’s appearance on Meet the Press but before Obama’s announcement, a Casey spokesman told the Lehigh Morning Call that Casey remains opposed to gay marriage. (He’s also pro-life, for the record).

Casey is up for re-election in the crucial swing state of Pennsylvania, which went for Obama in 2008 and where the president is currently polling ahead of Romney. His opponent, Republican Tom Smith, is opposed to both gay marriage and civil unions—but like Obama, would leave that decision up to the states.

Senator Claire McCaskill, D-Missouri

McCaskill is also up for re-election in a very tough swing state that went (narrowly) for John McCain in 2008. She, too, voted to repeal DADT and also opposes a constitutional amendment banning gay marriage. She supports civil unions—but seems to be a dedicated opponent of gay marriage.

In 2009, she voted against a Republican gun-rights amendment that would allow licensed gun owners in one state to legally carry that gun in all other states—because, she said, it might set a precedent for gay marriage license reciprocity too.

Senator Bill Nelson. D-Florida

Another senator up for re-election in a crucial swing state that went for Obama in 2008, but twice** for George W. Bush (you know what the asterisks are for). Nelson, like the rest, voted to repeal DADT, and also rejected a Republican attempt to strip protections for LGBT Americans from the Violence Against Women Act. He was even honored this month as a “Champion of Equality” by SAVE Dade, a leading gay rights group in South Florida.

Nelson, however, opposes gay marriage and even supported Florida’s ban on it. He is a former chairman of the National Prayer Breakfast and speaks often of his Christian faith. He does not have a position on civil unions, as far as I can tell.

Senator Debbie Stabenow, D-Michigan

Senator, up for re-election in a (sort-of) swing state, against DADT, for protecting LGBT Americans in the Violence Against Women Act—you know the drill by now.

Stabenow is against gay marriage, however, and refuses to challenge Michigan’s ban on same-sex marriage. For some reason, rabid anti-gay marriage candidates keep running against her, which is perhaps leading her to feel boxed in—but she’s probably safe to come out for it in Michigan if she so chooses.

Representative Steny Hoyer, D-Maryland

Hoyer is the second-highest ranking Democrat in the House, and represents a state where the legislature recently passed a bill to legalize same-sex marriage. When that measure was approved, Hoyer said he believed Obama would “applaud” it—but never actually applauded it himself.

Despite a strong record on things like DADT and a very safe House seat, Hoyer has never renounced his 1996 support of the Defense of Marriage Act and has not expressly supported gay marriage. When asked this week by New York magazine whether he supported gay marriage in light of Biden’s comments, his office dodged and wouldn’t give a firm answer.

UPDATE: Hoyer announced his support for gay marriage on Thursday afternoon: “Because I believe that equal treatment is a central tenet of our nation, I believe that extending the definition of marriage to committed relationships between two people, irrespective of their sex, is the right thing to do and will not, in any way, undermine the institution of marriage so important to our society nor impose a threat to any individual marriage. It will, however, extend the respect due to every one of our fellow citizens that we would want for ourselves and our children.”

Representative Jim Clyburn, D-South Carolina

Clyburn is the third-ranking Democrat in the House and the highest-ranking black elected official in the country not named “Barack Obama,” so his support will be interesting to watch. He supported the repeal of DADT and opposed the constitutional amendments defining marriage as between a man and a woman, but also voted for the Defense of Marriage Act in 1996.

He has since skillfully avoided taking any position whatsoever on gay marriage. New York magazine hassled his office for three days this week and got no response; and Christine Johnson, the executive director of South Carolina Equality, told the magazine that her organization “was unable to find any evidence that Clyburn has ever taken a position on the issue one way or the other.” 

UPDATE: Clyburn, too, has now switched, telling MSNBC that despite growing up in a "fundamentalist Christian parsonage," he has decided that same-sex couples should be able to get married. Clyburn actually went further than Obama by saying it’s not a matter that should be left up to the states. "If you consider this to be a civil right, and I do, I don’t think civil rights ought to be left up to a state-by-state approach," he said.

FINAL UPDATE: This article previously contained a reference to Senator Jack Reed of Rhode Island—but late Wednesday, he changed his position too. "I’ve been thinking and deliberating about this for many, many months," Reed told the Providence Journal. "I believe it’s appropriate to support same-sex marriage and as a result to support the Respect for Marriage Act."