The Republican Party spent $40 million to throw an unprecedented midterm convention in Texas a few weeks ago.

It was a bet born of desperation. With Democrats dominating the midterm polling all year and leading across nearly every competitive Senate race, the GOP went all in on the spectacle, hoping a polling bounce would shock its campaign back to life. Party conventions in recent cycles typically produce a 1- to 2.5-point bounce — a modest margin, but big enough to potentially save the Senate.