Both Flake and Corker have said they are not running for office, making them immune to political fallout if the tax bill fails to pass. Senators who are not giving up their seats began to balk last night at "the huge influence guys who aren't answerable to voters" were having on the process, according to one senior Republican staffer.
"We have the votes", McConnell said.
Daines and Johnson announced their support for the Bill on Friday after winning more tax relief for non-corporate pass-through businesses.
Because the House passed a different tax-slashing bill, the probable effect of Senate approval - provided the House doesn't pass the Senate's version - would be a conference committee in which lawmakers from both chambers fashion a compromise that could include elements of either bill.
Until late last night, it appeared that Flake and Corker had found a way to vote for the bill. Whether that is enough to bring her on board remains uncertain, but if Flake and every other Senate Republican save for Sen. That unexpected turn cast into doubt the support of Corker and Flake, prompting Senate leaders to call off plans to vote Thursday night.
But on Thursday - the same day the nonpartisan scorekeeper for tax bills said the Republican plan would add $1 trillion to the national debt even after accounting for growth - the trigger plan collapsed. The House has passed a version of its own and has scheduled a vote for Monday to set up a conference committee to resolve the differences between the two bills.
Late in the day, however, three Republicans, led by Senator Bob Corker of Tennessee, clung to a demand that proposed tax cuts would be pared back if future US economic performance did not meet projections. Without the deduction, Collins said, it would be "very problematic for me" to vote for the bill.
At stake is a top priority for President Donald Trump and a Republican Party that considers passage of the measure the best way to preserve the GOP's congressional majorities in next year's midterm elections. "That disparity between the USA tax code and foreign tax rates has literally chased jobs and wages out of this country".
Daines reached an agreement with leadership to raise the amount of pass-through income business owners can deduct.
Johnson said Friday that he was won over after GOP leaders offered to boost that deduction to 23 percent.
Corker, a deficit hawk from Tennessee, stalled momentum on the tax bill on Thursday by demanding Republicans look for more ways to keep the bill from ballooning the deficit. GOP leaders' main concern was winning over the hawks anxious about adding more red ink to the mounting $20 trillion deficit.
Flake said the "trigger" tax increases would raise about $350 billion over 10 years, though he didn't specify which taxes would go up.
Mr. Corker had been pushing for leaders to include a fiscal "trigger" in the package that would wind down some of the planned tax cuts if they didn't generate the amount of economic growth Republicans are projecting.
Details were sketchy but lawmakers said on Friday changes were being made to provisions dealing with the federal deduction for state and local property tax, a cut in the corporate income tax rate, the alternative minimum tax and a one-time tax on foreign profits held offshore by multinational corporations.
After months of negotiations and false starts, Republicans finally seem prepared to pass their most sweeping rewrite of the US tax code in three decades.
Unlike the House bill, for example, the Senate bill would end the insurance mandate at the core of the Affordable Care Act.
The Senate bill would need to be merged with a House-passed measure, which leaders hope to quickly finish in the days ahead.