Even a partial report from the Congressional Budget Office was enough to apparently tip the scales against the latest Republican effort to overhaul the Affordable Care Act and prompted a crucial senator to announce she cannot support the bill, seemingly sinking its chances.

The CBO said Monday that the bill offered by Sens. Lindsey Graham (R-S.C.) and Bill Cassidy (R-La.) would meet the requirements for fast-track consideration in the Senate, but that “millions of additional people would be uninsured,” if the bill became law.

Within minutes of the report’s release, Sen. Susan Collins (R-Maine) tweeted her opposition to the bill, becoming the third Republican to do so. Republicans can afford to lose only two votes to pass the bill.

In a statement, Collins said the CBO’s analysis, “incomplete though it is due to time constraints, confirms that this bill will have a substantially negative impact on the number of people covered by insurance.”

Unlike earlier GOP proposals, the CBO did not have enough time to fully evaluate the impact of the proposal unveiled earlier this month. “In the short time available, CBO and [the Joint Committee on Taxation] could not complete a full analysis on the effects of this legislation on the federal budget,” the report said.

There’s another complication — the version of the proposed legislation analyzed by the CBO is not even the latest version. Sponsors made changes over the weekend to try to win votes from fence-sitting moderates and conservatives, including Ted Cruz (R-Texas), Mike Lee (R-Utah), Lisa Murkowski (R-Alaska) and Collins.

Asked at a Senate Finance Committee hearing Monday if the version on his website was the one the Senate might vote on, Cassidy replied, “I hope so.”

The CBO said that fewer people would be covered because subsidies that help people pay premiums and other financial aid would be eliminated, and individuals would no longer be required to have insurance or pay a fine.

It also said the bill would dramatically change the Medicaid program. “All told, federal spending on Medicaid would be reduced by about $1 trillion over the 2017-2026 period under this legislation, and the program would cover millions less,” the report said.

Senate Majority Leader Mitch McConnell (R-Ky.) has said if someone brings him a health proposal that can gain the 50 votes needed to pass under the budget reconciliation process, he will resume consideration of the bill that he pulled from consideration in July.

The Senate’s ability to use the fast-track process, however, expires at the end of the fiscal year, which is Saturday.

Collins’ announcement makes it almost impossible for senators to reach that threshold, unless they can persuade either Sen. John McCain (R-Ariz.) or Rand Paul (R-Ky.) to change their minds. They pledged to vote no last week.