“This is disgusting, vile and disqualifying,” she said in a statement. “No woman should ever be subjected to this type of obscene behavior, and it is unbecoming of anybody seeking high office.”

Early on, she supported Senator Marco Rubio’s presidential bid. In ensuing months, she remained resolutely reticent on Trump, simply never uttering his name in trying to avoid any political undertow that he might create. But after the release last week of a recording in which Trump boasted in vulgar terms about assaulting women, Comstock was among the first Republicans to call on him to step down.

LANSDOWNE, Va. — Like many Republican candidates, Representative Barbara Comstock is trying to prevent Donald Trump’s problems from becoming hers.


Comstock is hoping her disavowal will be enough. The outcome here in Loudoun County, which in recent years has been seen as a bellwether in presidential politics, will provide a measure of any down-ballot damage that Trump’s contentious candidacy may have caused.

Comstock’s wealthy, highly educated district in the suburbs of Washington is a diversity-rich hub of government largesse, where federal contractors commute past Buddhist temples, mosques, and churches that offer services in Korean.

“If the Democrats have any prayer of taking the House, and I think it’s just a long shot, they’ve got to win this seat,” said Thomas M. Davis III, a former Republican congressman who represented portions of Comstock’s district.

So far, many analysts say, there is scant evidence that voters will penalize candidates because of Trump.

“Believe it or not, it hasn’t changed matters all that much,” said David Wasserman, the House of Representatives editor for the Cook Political Report. He has forecast that Democrats could pick up as many as 20 seats, 10 short of the number needed to regain control of the House.

Polls have shown that voters are willing to separate their support for certain House and Senate candidates from their feelings about the top of the ticket. In an effort to bolster Comstock and other vulnerable Republicans, the Congressional Leadership Fund, a super PAC aligned with Republicans, announced Friday that it would invest an additional $10 million into 15 targeted races, including hers.


Speaker Paul D. Ryan of Wisconsin also has tried to ensure his party holds its House majority, offering a policy agenda and promising appearances in dozens of cities to lend his fund-raising power.

His campaign said on Thursday that Ryan had raised $15.4 million in the third quarter, collecting more than $48.2 million in 2016. He has transferred more than $31 million of that to the National Republican Congressional Campaign Committee.

Ryan — having disinvited Trump from their first planned joint appearance in Wisconsin last weekend after news of the recording broke — effectively cut his members free on Monday, saying he would not defend nor campaign with Trump. He has instead shifted his focus to the argument that Republicans need to be reelected to serve as a bulwark against a potential President Hillary Clinton.

Representative Nancy Pelosi of California, the Democratic leader, has proved once more to be a fund-raising powerhouse, raising $34.6 million for House Democrats in the third quarter and $127.7 million this election cycle, the Democratic Congressional Campaign Committee said on Wednesday.

But Democrats have a steep climb. With 247 seats, House Republicans hold their largest majority since 1931.