WASHINGTON — Republicans saw the poisonous fight over Brett M. Kavanaugh’s Supreme Court confirmation as pure gold in the midterm elections, calling it “Kavanaugh’s Revenge.” Senator Bob Casey saw it a little differently in his own re-election bid — as a less-than-decisive issue in what was supposed to be a marquee race.

“I think because health care was such an overriding factor, it was down the list,” said Mr. Casey, the Pennsylvania Democrat, who won easily despite his strong opposition to Judge Kavanaugh in a state won by President Trump two years earlier. Mr. Casey’s performance in the Philadelphia and Pittsburgh suburbs — an improvement from previous elections — suggests that the Kavanaugh fight could have instead benefited him by turning out supportive voters.

In the end, the most contentious Supreme Court confirmation drama in decades resulted in a split midterm decision that suggests that Democrats might have gained ground in their fledgling efforts to make the court as mobilizing an issue to their voters as it has long been to Republicans.

The conservative backlash to the fight seemed to help Republicans capture three Democratic Senate seats in conservative Indiana, Missouri and North Dakota — but Republicans might have grabbed the seats regardless of the uproar over Judge Kavanaugh. The backlash could have influenced the narrow Democratic Senate loss in Florida as well. And the sole Democratic senator who supported Judge Kavanaugh, Joe Manchin III in West Virginia, won in one of Mr. Trump’s strongest states.