Most Senate Republicans are opposed to extending "Cash for Clunkers" -- the system for trading in older, less-fuel efficient vehicles for newer, greener ones --- but it's unclear if GOP'ers will filibuster a House-passed bill that infuses the progrma wtih $2 billion more from the stimulus.

The program ran out of money within days of coming online, and White House Presss Secretary Robert Gibbs has said it will likely run out if the Senate does not act.

A spokesman for Senate Majority Leader Harry Reid, D-NV, says don't expect the Senate to consider it either today or tomorrow. Reid, himself, said he's still not sure how he will proceed.

Some leadership aides have said they are in consultation with the White House on how to move forward. They will either try to move the House bill or a new Senate product, or it's possible there would be an administrative solution -- that would not require Congressional action.

Also -- turns out Sen. John McCain, R-AZ, WILL let a Clunkers bill come up for debate.   He told Fox, emphatically, "I am strongly opposed to it, but I will not filibuster it."

McCain said, instead, if Reid allows amendments (which is doubtful - give that the Senate is only in this week before departing on a monthlong recess), he will offer one that calls for a pause in the program "while we find out who's gotten what." from it.