Senators are making one final plea to their colleagues Tuesday morning as they prepare for a vote to repeal the military’s “don’t ask, don’t tell” policy.

With Republicans promising to filibuster the vote, Democrats are desperately trying to convince moderate Republicans to break with their party and vote to repeal the 17-year-old law that President Obama said, “denies Americans the right to serve the country they love because of who they are.”

But with midterm elections just six weeks away, even moderate Republicans who have previously supported the repeal of DADT are hesitant to help the opponent.

Senator Susan Collins, a Republican from Maine, made an impassioned speech Tuesday morning calling DADT unfair and morally indefensible, but said she will still join her party in the filibuster.

Collins has been the Democrats' primary target in their effort to win the 60 votes needed to proceed with the repeal, but she said that Senate Majority Leader Harry Reid’s refusal to allow unlimited amendments to the bill would stop her from voting with the Democrats.

With two other targeted Republicans promising Tuesday to join the filibuster, the numbers for Democrats look unfavorable. President Obama called for the law’s repeal in his January State of the Union address, but the White House has been mum on the issue in recent days. If the vote fails, repeal could be pushed back until next year.

The vote is scheduled for 2:15 p.m. Eastern. For updates from the Senate floor, click here.

To see footage from Lady Gaga’s rally for repeal, click here.

Reach reporter Helen Tobin here.

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