Scott Moore, a real estate investor in Henrico County, who said he loved “everything” Mr. Trump was doing, predicted Democrats’ timing on impeachment would backfire and motivate Republicans to turn out. “I think that’s on everybody’s mind,” he said, adding that he thought Democrats were “desperate to come up with something, anything, because they don’t have a candidate that can beat him right now.”

But Kim Young, a counselor for troubled youth who also lives in the county, said his vote for Democrats would be “100 percent” a message to Mr. Trump. “It’s just to let you know that your term is coming up and even if the impeachment doesn’t happen, I’m not going to stand by and listen to another four years,” he said.

Siobhan Dunnavant, a Republican state senator seeking re-election in Henrico County, in one of the state’s most competitive races, has distanced herself from the president. Her yard signs in rural areas identify her as a Republican, but the party label is omitted in suburbia.

Four years ago, in the pre-Trump era, Ms. Dunnavant, an obstetrician-gynecologist, won election by 20 points. Now she faces a tough challenge from Debra Rodman, a freshman member of the House of Delegates who was stirred to run in 2017 by opposition to Mr. Trump. Ms. Rodman said her internal polling showed a tied race.

Ms. Rodman was unknown two years ago. “This time around, I get to the door, they’re like, ‘Hey, honey, come down, Debra Rodman’s at our door,’” she said. “They’re really just motivated by what’s going on at the top, but also in the White House.”

The race has attracted more TV spending than any in the state, $2.1 million, much of it for negative ads: Ms. Rodman accuses her opponent of seeking to restrict abortion and opposing gun safety; Ms. Dunnavant attacks Ms. Rodman as a “radical” who favors “taxpayer-funded elective transgender surgeries.”

In an interview, Ms. Dunnavant said that state issues were top of mind for most voters, but that impeachment loomed in the background. “I do think people are saying, why are the Democrats putting us through this a year away from the election?” she said. “And why aren’t they getting anything done? And then they come back to the fact that in Virginia, we still do get stuff done.”