UPDATED Wednesday, December 8, 2010 at 5:45pm.  A vote on Don’t Ask Don’t Tell is unlikely to happen tonight.

Senate Majority leader Harry Reid has called for a vote on the repeal of Don’t Ask Don’t Tell after 6 o’clock tonight, meaning it’s do or die for the legislation. Though this is a procedural vote, if DADT doesn’t get past this hurdle, the legislation is likely dead in the water for years.

For Illinois Republican Senator Mark Kirk, this isa chance to show his true colors. As a congressman, Kirk said no to DADT. It was, perhaps, a nod at the conservatives he had to win over in his own party in order to be taken seriously as a primary candidate. That vote was considered both cowardly and opportunistic by many because it seemed contrary to Kirk’s more moderate stances.

But from the moment he became the GOP standard bearer, Kirk has been signaling openness. As late as a week ago, he was saying he was going to read “every page” of the Pentagon’s DADT study in order to make up his mind. The study makes clear that the rank and file doesn’t think repealing DADT is much of a big deal.

Though the White House, which claims 58 Dem votes in hand for repeal, has him listed as undecided as of this afternoon, a source in Senator Joe Lieberman’s office tells me Kirk’s is one of the 60 votes the Connecticut independent is counting on for repeal. The Huffington Post is currently reporting that Kirk is actually reading the Pentagon study and, according to an anonymous staffer, that calls to his office heavily favor repeal of DADT.

In the past, Kirk has been one of the few Republicans to get an overall decent rating from the Human Rights Campaign: 75 percent. In spite of being a big Bush supporter, Kirk had the fortitude to oppose a constitutional amendment banning same sex marriage and supported ending job discrimination based on sexual orientation. His ex-wife and still close friend, Kimberly Vertolli, a former Naval intelligence officer, is a passionate supporter of repealing DADT.

Like all GOPers in Congress, Kirk signed a letter last week committing to resolve the current tax issues and fund the federal government before tackling anything else, including both the DREAM Act and DADT. DADT is part of the defense authorization bill.

“Congress’s top priority should be to prevent a large tax increase from hitting families and small business employers on January 1st,” said Kirk spokesperson Kate Dickens. “Senator Kirk supports the president’s bipartisan tax bill and very modest legislation to continue funding the government. These two measures should take precedence before considering non-economic legislation, including items Senator Kirk’s supports like the 9/11 victims health bill.”

Besides, if his constitutents are supporting repeal, there’s not much to lose on the homefront.

UPDATE: Alaska Sen. Lisa Murkowski, who doesn’t owe much to her caucasing party after her bruising re-election fight, has released a statement in support of repealing DADT, which could help make Kirk’s decision easier. Murkowski was a previous no vote who’d moved to unsure.

According to Murkowski: “America is the loser when it denies those who are willing to make the great sacrifices demanded of our men and women in uniform the opportunity do so on grounds of sexual orientation. I agree with Defense Secretary Gates’ view that the military can successfully implement a repeal of the ‘Don’t Ask, Don’t Tell’ law provided that proper preparations are implemented.”

(above photo by Bill Healy)