I think I have this straight. The Senate will vote Tuesday on whether to break a Republican filibuster aimed at blocking consideration of the 2011 National Defense Authorization Act. The Republicans have turned against defense spending? No, they’re against a provision of the bill that would start to repeal the military’s anti-gay Don’t Ask, Don’t Tell policy.

[2nd Update, later on Tuesday afternoon: ThinkProgress has an excellent summary of the Republican smackdown, including Sen. Susan Collins’ tortured logic.]

[Update, Tuesday afternoon: 43 senators, including all 41 Republicans, voted to filibuster the bill as long as it contains the anti-DADT provision. The 56 senators who wanted to debate the bill with the anti-DADT provision were thus outvoted. In U.S. Senate math, 43 in the negative is more than 56 in the affirmative. So the bill is stopped for time being, meaning no money to pay the troops.

[h/t to The Progressive Pulse: Sen. Kay Hagan, D-NC, was one of the 56 votes for taking up the bill. Sen. Richard Burr, R-NC, was on the other side, obviously. Two Democrats voted with the Republicans — Mark Pryor and Blanche Lincoln, both from Arkansas. Also voting with them was Majority Leader Harry Reid, D-NV, but that’s a technicality — his “pro-filibuster” vote allows him to move for cloture at some future point. The real vote, in other words, was 42-57. But again, 57 votes isn’t a majority in the Senate.]

According to the indispensable Pam’s House Blend, advocates of repealing DADT need at least two Republican votes to go along with 58 Democrats — it takes a supermajority of 60 votes to get stuff done in the antediluvian Senate.

So far, the advocates have just one: Sen. Susan Collins of Maine is the one Republican who’s pledged to vote for the repeal of DADT — that is, with the Democrats for breaking the filibuster. They were hoping the other Maine Republican, Olympia Snowe, would join Collins, but today she announced that she probably won’t.

If the filibuster is broken, the next order of business will be a vote on whether to include the pro-immigration reform DREAM Act in the Defense bill. It’s a winnable fight, according to Chris Bowers of DailyKos — six Republicans have either sponsored this bill or voted for it previously. Bowers says: Call your senator.

Here’s an update from the SEIU on which senators stand where on the DREAM Act. Both of North Carolina’s senators, Hagan (D) and Burr (R), are listed as undecided. It’s pretty clear to other advocates, though, that Burr is a definite no. Hagan? She’s expressed support for the concept, but not for the amendment — she would prefer a DREAM-like bill to be part of a comprehensive immigration reform package.

Yes, but there is no comprehensive package in sight. It’ll be interesting to see what Hagan does if the DREAM act comes up. It may or may not — the DADT measure is said to be 50-50 as wavering Democrats do what they do, which is waver, and Republicans do what they do, which is obstruct.

This would be a good day (morning) to call your senators.