Senate Majority Whip John Cornyn on Friday said the GOP has the votes to pass a tax overhaul, but added they were still working to bring Sens. Jeff Flake of Arizona and Bob Corker of Tennessee onboard.

“We haven’t given up,” the Texas Republican said. His comments indicate the GOP has 50 votes, and can call in Vice President Mike Pence to break a tie, but would prefer to get all 52 Republicans on board. 

The endorsement of the GOP tax bill by two more Republican senators on Friday morning provides major momentum heading into an expected vote on the historic overhaul. However, some GOP senators have not fully committed to supporting it, providing a measure of fluidity to the negotiations. 

Sen. Steve Daines of Montana will support the  bill after successfully lobbying for changes in the legislation to provide greater benefit to pass-through businesses, his office announced on Friday.

The changes were enough to also get the vote of Sen. Ron Johnson, an aide to the Wisconsin Republican said.

A Daines aide said he is supporting the bill because a revised version will now include a 23 percent income deduction for pass-through business owners, up from 17.4 percent in a prior version. 

Watch: McConnell — Tax Bill a ‘Once in a Generation Opportunity’

“After weeks of fighting for Main Street businesses including Montana’s farmers and ranchers, I’ve decided to support the Senate tax cut bill which provides significant tax relief for Main Street businesses,” he  said in statement. 

As of Thursday evening, GOP leadership was negotiating a number of revisions to try to win over other skeptical Republican lawmakers, including Corker and Flake. Both have raised concerns on the bill’s impact on the federal deficit. 

Sen. Susan Collins of Maine is also pushing for the inclusion of a provision to allow individuals to deduct up to $10,000 in property tax. The House-passed version includes a similar measure. Republican aides say it is likely the proposal will be incorporated into an updated bill, since it is assumed it would have to be added into a final negotiated package between the two chambers. 

Schumer: GOP ‘Abandoning’ Its Principles With Tax Bill

Ryan McCrimmon contributed to this story.