President Donald Trump scored a major win Thursday as establishment Republican John McCain agreeing to get on board a sweeping revamp of the nation's tax code. Majority Leader Mitch McConnell expressed confidence of final passage by week's end, a major goal of the White House.

The GOP had the momentum for delivering a major legislative and political win for Trump after the bill cleared a procedural hurdle on a 52-48 vote late Wednesday.

"We're heading down the homestretch," McConnell, R-Ky., told reporters on Thursday. McConnell said he expected a vote either late Thursday or early Friday.

McCain, who controversially derailed the GOP effort to dismantle Obamacare last summer, said Thursday he would back the tax bill, a major boost for the legislation.

"It's clear this bill's net effect on our economy would be positive," McCain said in a statement. "This is not a perfect bill, but it is one that would deliver much-needed reform to our tax code, grow the economy, and help Americans keep more of their hard-earned money."