But President Trump and Republicans risk becoming victims of their own success. Without the specter of a liberal court to motivate conservative voters anymore, they may find themselves without the issue that played a crucial role in Mr. Trump’s unexpected victory four years ago and has fortified his political base throughout a tumultuous first term.

“It’s like the dog catching the car,” said Charlie Cook, editor of the nonpartisan Cook Political Report, which handicaps elections and is forecasting a difficult environment for Republicans up and down the ballot…

Privately, Republicans have expressed some disappointment that there was very little of the partisan fury and indignation that erupted during the confirmation of Justice Brett M. Kavanaugh in 2018. The Kavanaugh hearings included a sexual assault allegation against him from his high school years, and became a remarkably emotional and divisive culture war clash that raised questions of class and privilege, gender roles and the presumption of belief extended to victims of sexual assault.