I just spoke to a Senate Republican source and things aren’t looking good. Republican leadership believes that the Dems have a handful of Republicans boxed in. As for who might cave, there are no real surprises. Speculation is falling on Snowe, Collins, and Specter, and possibly one or two other Republicans. They’re going to work on some deal –Republican leadership doesn’t know what it is yet–to give the moderates cover for going along, but the end result will still be a package in the neighborhood of $800 billion. They expect this final amendment to be introduced in some broad outline today, and that might be the last amendment allowed.

Dems are also strong-arming Republicans with parliamentary tactics — right now it’s debate only on the floor of the Senate, and are not allowing any more amendments to be offered. (The same trick Senate Dems used during the immigration debate.)

“They’re following the same strategy they’ve used to pass every other bad bill, using fear and panic to railroad things through and waiting until the end of the week and trying to control the news cycle,” the source said.

Dems will probably file cloture tonight, they’ll have a vote on Sunday, and the final vote will likely fall on Monday.

In the end, the source says the Senate GOP’s big fear is along the lines of what Jonah outlined in his column today–that this emergency spending will become part of the baseline, growing government to a staggering degree in a single impetuous leap.