Sen. Susan Collins, R-Maine, said she will vote against advancing the Senate health care bill.

Collins issued three tweets voicing her opposition to the bill Monday night.

“I want to work with my GOP and Dem colleagues to fix the flaws in ACA (Affordable Care Act). CBO (Congressional Budget Office) analysis shows Senate bill won’t do it. I will vote no on mtp (motion to proceed),” she tweeted.

Her other tweets mention how the CBO forecasts that 22 million fewer people would have insurance by 2026 under the Senate bill than if the ACA remained in place, and that Medicaid cuts will hurt America’s most vulnerable. Collins also tweeted that the Senate bill “doesn’t fix ACA problems for rural Maine. Our hospitals are already struggling. One in 5 Mainers are on Medicaid.”

Collins on Monday joined at least two other Senate Republicans – Sen. Rand Paul of Kentucky and Sen. Dean Heller of Nevada – who have said they will not support a procedural motion to consider the bill that would repeal and replace the Affordable Care Act.

Several other Republicans said last week that they can not support the bill in its current form. The vote on the bill could come as soon as Tuesday or Wednesday.

Collins and fellow Republicans who oppose the health bill cast doubt on the chances Senate Majority Leader Mitch McConnell will get it through the Senate this week, before Congress breaks for the July Fourth recess. With Republicans holding a 52-48 edge in the Senate, McConnell can only afford to lose two votes and still have Vice President Mike Pence break a tie.