Collins, who had raised “very serious concerns” about the bill before the report’s release, said Monday that she wants to work with Republicans and Democrats to “fix the flaws” in the Affordable Care Act. But, she said, “CBO analysis shows Senate bill won’t do it.”

“CBO says 22 million people lose insurance; Medicaid cuts hurt most vulnerable Americans; access to healthcare in rural areas threatened,” Collins said in a series of tweets. “Senate bill doesn’t fix ACA problems for rural Maine. Our hospitals are already struggling. 1 in 5 Mainers are on Medicaid.”

I want to work w/ my GOP & Dem colleagues to fix the flaws in ACA. CBO analysis shows Senate bill won't do it. I will vote no on mtp. 1/3

— Sen. Susan Collins (@SenatorCollins) June 26, 2017

CBO says 22 million people lose insurance; Medicaid cuts hurt most vulnerable Americans; access to healthcare in rural areas threatened. 2/3

— Sen. Susan Collins (@SenatorCollins) June 26, 2017

Senate bill doesn't fix ACA problems for rural Maine. Our hospitals are already struggling. 1 in 5 Mainers are on Medicaid. 3/3

— Sen. Susan Collins (@SenatorCollins) June 26, 2017

The bill, which is opposed by all Democratic senators, has also faced criticism from a handful of Republicans. Alaska Republican Sen. Lisa Murkowski, who has voiced skepticism about the bill, told CNN after the CBO report that she needed more information before she could decide how to vote.

“I don’t have enough data, in terms of the impact to my state, to be able to vote in the affirmative,” Murkowski said. “This is big stuff, and so making sure that we get it right is something that I have said is an imperative.”

With Democrats uniformly opposed, Senate Majority Leader Mitch McConnell can only afford two defections for a vote he’s hoping to hold this week.