For that matter, neither the House nor Senate has held serious hearings on any part of the tax plan. No other modern piece of major legislation has ever been so rushed — except for the health care bill that McCain doomed. Congressional leaders are rushing this bill because they know it’s unpopular, and their haste is making a mockery of the institution that McCain holds dear.

For Collins and Murkowski, the principle is health care. More specifically, it’s decent health care for the working-class families who dominate their home states of Maine and Alaska. The two of them were the most consistent Senate opponents of the bills this year that would have taken insurance away from millions.

Image Senator Susan Collins of Maine. Credit... Robert F. Bukaty/Associated Press

Now the tax bill threatens to undo some of their good work.

The repeal of the mandate would create turmoil in insurance markets, because fewer healthy people would sign up for coverage, raising prices for everyone else. Collins opposes the measure for that reason, while Murkowski supports it if it’s paired with other measures to stabilize health markets. But those measures would need to be sweeping to make up for the damage.

Then there are Corker, Flake, Lankford and Moran. Their principle is the deficit. “We don’t want to increase the debt and deficit as a result of tax cuts,” Moran said. If the bill adds “one penny to the deficit,” Corker said, he wouldn’t support it.

The current Senate plan adds more than 100 trillion pennies to the deficit in the first decade, according to the official estimate. And that estimate is probably low, because the plan depends on a budgetary gimmick. The bill’s authors set the most popular tax cuts to expire, knowing that a future Congress may extend them. Corker and Flake have correctly called out this ruse. They and their colleagues would undermine any claim to fiscal conservatism if they voted for any bill that resembles the current one.