The votes will test the abilities of McConnell and Schumer to unify their sides, and likely, to negotiate with each other afterward. In other dramatic fiscal showdowns over the past decade, the Senate has almost always been the chamber that found the bipartisan solution as the House hit roadblocks, from the Wall Street bailout of 2008 to reopening of government after the 2013 shutdown. But those were crises that predated President Trump’s mercurial presidency.

In effect, the defeat of both measures would demonstrate in the most concrete manner yet that what both sides have been pushing for is not possible in the Senate, and that some new compromise must be forged to pass the chamber.

Such a scenario might entice Trump to offer more concessions to Democrats while serving as a counter to Democrats’ insistence that there is overwhelming support for their plan, according to a Senate Republican leadership aide, who spoke on the condition of anonymity to be candid.