“On the next big thing, we can’t fail,” said Senator John Thune of South Dakota, the third-ranking Senate Republican. “We have to double down on tax reform.”

There is no question the lift ahead is heavy. Congress has yet to pass a budget, something that should have been done this spring. Without measures to fund the government, a shutdown threat, which has become a feature as endemic to Washington as the annual cherry blossom run, will loom. Democrats in the House and Senate may make their own mischief with the debt ceiling, tying it to the Republicans’ tax bill.