WASHINGTON After the Congressional Budget Office dealt another blow to the Republican health care plan, Senate GOP leaders on Monday night scrambled to figure out a way forward for a bill already on shaky ground.

Republican leaders seemed to have no margin of error left.

Sen. Susan Collins (R-Maine) announced Monday night she will oppose the GOP bill, joining Sen. Dean Heller (R-Nev.). That leaves Senate Majority Leader Mitch McConnell (R-Ky.) without the option of losing another Republican. The problem for McConnell is that he may have already lost senators, as Sen. Rand Paul (R-Ky.) and other conservatives increasingly trash-talk the GOP plan for not lowering premiums.

Its a terrible bill, Paul told reporters Monday night.

Its worse to pass a bad bill than to pass no bill, Paul continued. And 2018 is going to roll around and people are going to ask themselves, Are my premiums lower? and theyre going to find out, You know what, my premiums still went up 25 percent.

Paul said he would oppose a motion to proceed without assurances to improve the bill, and suggested there are other conservative senators who also will hold out.

McConnell hasnt committed to holding a vote on the GOP bill before senators leave for a July 4 recess. The No. 2 Senate Republican, Majority Whip John Cornyn (R-Texas), said Monday he was closing the door on a delay, saying insurers need to come up with plans for 2018.

But Cornyns pledge was before Collins came out against the bill. While Republican leaders have faced a vote problem all along, putting the bill to a vote now, only to see it fail on the floor, could complicate efforts in the future. Its a question for leaders: Do they think theyre better served by a delay than by a failure?

Republicans find themselves in this position after the CBO predicted Monday afternoon that the Senate bill would insure 22 million fewer people and cut $772 billion from Medicaid. While the most reliable Republicans were happy to cast doubt on the projections (Sen. Pat Toomey of Pennsylvania), or embrace the report as welcome news of deficit savings (Sen. James Inhofe of Oklahoma), senators who remain question marks on the bill seemed to take the report seriously.

Even Sen. Ted Cruz (R-Texas) was citing the report for its conclusions that premiums would not go down, though he wouldnt answer reporters on whether he would vote against the bill or the motion to proceed if the legislation came up for a vote this week. Sen. Ron Johnson (R-Wis.) was also cagey, but warned that leaders better not count on his vote this week. Johnson signed a statement last week with Mike Lee (R-Utah), Cruz and Paul suggesting they opposed the bill in its current form.