Such efforts have had mixed results so far, and it remains to be seen how much the new audio and video tape of Trump talking about groping and kissing women will change that. Several GOP Senate candidates in top-tier races, including New Hampshire, announced over the weekend they were pulling support from Trump. House Speaker Paul Ryan declared Monday that he will not campaign for or defend the nominee, giving House Republicans permission to dump him.

But officials in both parties say they will not know the extent of the damage to Trump, or the impact on down-ballot races, until polling results filter in later this week and next.

For now, though, the reaction is elation on the part of Democrats—and concern from Republicans.

House Democratic leader Nancy Pelosi told upbeat House Democrats on a conference call Tuesday that if the election were held today, Democrats would take back the House—although few are quite that optimistic, given the Republicans’ 246-186 seat advantage.

“We are expanding our universe of opportunities,” Rep. Ben Ray Lujan, chairman of the Democratic Congressional Campaign Committee, said on the same conference call, pointing to new polling showing Democrats had opened up the biggest advantage since Republicans shut down the government two years ago on the question of which party voters preferred to control Congress.

The comments were confirmed by a Democratic aide who spoke on condition of anonymity to disclose the private conference call.

In an open House seat in Wisconsin, Democrat Tom Nelson is airing an ad using the new Trump audio and attacking opponent Mike Gallagher, who’s been favored to win. “Mike Gallagher still says we have to support Donald Trump. No, we don’t. We don’t have to support Mike Gallagher either,” the narrator says.

In Minnesota, Democratic challenger Terri Bonoff has an ad hitting GOP Rep. Erik Paulsen for not distancing himself from the Republican presidential candidate until now.

And in the New Hampshire Senate race, Democratic Gov. Maggie Hassan uses the new Trump footage, and a clip of Republican Sen. Kelly Ayotte saying during a debate that she would “absolutely” view Trump as a role model. Ayotte later said she misspoke, and on Saturday she withdrew her endorsement of Trump.

The Trump tape “gives us an opportunity with any voter who happens to be female,” said Alixandria Lapp, executive director of the House Majority PAC, which helps Democratic candidates. She later amended the remark to include “anyone who is human and decent” and added that the video “potentially depresses some Republican enthusiasm for going out to vote on Election Day.”

Republicans say that the potential for depressed turnout is one of the most concerning potential impacts of the tape. Center-right voters could just sit out the election and the few remaining undecided voters could all shift to the Democrats. Democrats need to pick up five seats to take back control of the Senate, or four if they retain White House control since the vice president casts tie-breaking votes.

Republican Senate candidates have tried all year to build their campaigns into insulated operations that can withstand the controversy of the day created by Trump. There’s evidence that the strategy has been working, as Republicans in Ohio, Nevada, Florida, Pennsylvania and elsewhere have been running ahead of Trump. But this latest controversy may test the limits of the GOP approach.

“The Democrats have invested millions of dollars trying to pin Donald Trump on our Senate candidates and I think they’ve had very little to show for it so far,” said Steven Law, president of the Senate Leadership Fund, a GOP super PAC focused on Senate races. A key concern now, Law said, is “whether there is a decline in voter enthusiasm on our side that could obviously have down-ticket ramifications.”

Josh Holmes, a GOP consultant close to Senate Majority Leader Mitch McConnell, said it would be “difficult but possible” for Republicans to retain Senate control if Trump is running behind Hillary Clinton by as much as 11 percentage points, the margin in an NBC News/Wall Street Journal poll conducted after the Trump comments came out but before the Sunday night debate.

But Republicans agree there is a limit to how far ahead of the GOP nominee their candidates can run.

And if Trump’s support continues to fall, it could encourage a spate of GOP House and Senate candidates to run ads touting themselves and a Republican Congress as the best way to check a Clinton presidency.