Democrats are ramping up their efforts to tie Republicans to Donald Trump’s flagging campaign, hoping to boost their chances of retaking control of the Senate. But so far there’s little evidence that Republicans are being dragged down by their controversial nominee.

GOP senators split last weekend, with several of them withdrawing support of Trump after the recording surfaced of him making lewd comments about women and boasting about making unwanted sexual advances; others condemned the comments while standing behind their nominee.

While Trump’s poll numbers nationally and in swing states were dropping last week, the polling for GOP candidates who still back Trump, and those who withdrew their support, stayed much the same as they did before Trump’s controversial remarks.

“It doesn’t feel like a whole lot has changed yet,” said Kyle Kondik, managing editor of Larry Sabato’s Crystal Ball at the University of Virginia. He added, however, that that could change if Trump continues his downward trajectory. “I still think there’s some time for some of this ticket-splitting that we’re seeing in polls to fade a little bit.

“Does he continue being down five to six points nationally?" Kondik said. "Or does he get better, in which case that could save some of these senators? Or does he get worse, in which case a lot of them might lose?"

Democrats said the impact may not be clear just yet, but they are confident Republicans will face backlash based on whether they pulled away from Trump.

“It’s hard to tell yet exactly what impact this might have, but without a doubt it has put the judgment of GOP senators and candidates supporting Trump in the spotlight and has kept it there,” said a Democratic strategist working on Senate races.

Republicans, on the other hand, have argued for months that voters view GOP senators through a different lens than Trump, and they believe that trend will continue. Andrea Bozek, a spokeswoman for Senate Republicans’ campaign committee, said Democrats were doubling down on a strategy that has yet to work in this election.

“Democrats had a fatal and fundamental flaw in their plan to take control of the Senate: Their efforts did not rely on having better candidates running better races than their opponents,” Bozek said in an email. “While Republicans have worked nonstop since day one of this campaign to build nimble, data-driven campaigns, Democrats have relied on political gravity from the presidential race to carry them across the finish line.”

In some of the most competitive races, there has been little change over the past week. Sen. Kelly Ayotte of New Hampshire has received perhaps the most attention for withdrawing her endorsement of Trump after she had previously said in a debate that he was “absolutely” a role model.

During another debate Friday morning, Ayotte faced questions about her decision to drop her support of the nominee, and her opponent, Gov. Maggie Hassan, criticized her multiple times for her previous support of him. But Ayotte defended her decision.

“First of all, I’ve renounced Donald Trump’s statements on many occasions on the issues that Gov. Hassan has identified, and I’ve clearly said where I stand on Donald and Hillary Clinton. I won’t be voting for either of them,” Ayotte said.

A poll released Friday — conducted entirely after Ayotte withdrew her Trump support — showed her up by a single percentage point in the race. A poll released Thursday — conducted both before and after she withdrew her Trump support — showed a tied race. Ayotte still leads in the RealClearPolitics average by 2.3 percentage points.

In Ohio, Sen. Rob Portman also withdrew his support from Trump over the weekend, but two polls conducted after that decision showed him leading that Senate race by 17- and 18-point margins.

In Nevada, the impact is slightly murkier. Rep. Joe Heck withdrew his support of Trump on Saturday and saw immediate backlash, with some Trump supporters booing him at the event where he took back his endorsement. A poll conducted on behalf of the campaign of his opponent, Democrat Catherine Cortez Masto, found Heck trailing by four percentage points, with nearly half of Trump supporters saying they were less likely to vote for him after he withdrew his endorsement.

But a poll released by the GOP super PAC Senate Leadership Fund the next day showed Heck with a three-point lead, with nearly 90 percent of Trump supporters still backing him.

In the most recent RealClearPolitics Average, Heck has fallen behind Cortez Masto by 2.0%

Though Trump’s decline hasn’t made a measurable impact on Republican Senate candidates yet, Kondik said they could start to see more problems if Trump continues to bleed support in the polls in the coming weeks.

“If it’s true that Clinton is going to win this presidential election — and I definitely think she’s favored right now — if that is the case, it would not surprise me if Democrats got a little momentum at the end and maybe flipped some seats" that didn’t look promising earlier, Kondik said.

Republicans, wary of the potential for late momentum, have begun highlighting the possibility that Clinton will win the White House, calling for voters to give the GOP control of Congress to provide a check on her administration.

Pennsylvania Sen. Pat Toomey, who never made clear whether he supports Trump, released an ad Tuesday accusing his opponent, Katie McGinty, of being the handpicked choice of national Democrats. McGinty, in a statement Friday, called the ad “pathetic.”

“I have a lot of disagreements with Donald Trump. I’ve been very clear about that,” Toomey says in the ad. “But what’s important for Pennsylvanians is having a senator who will stand up to any president’s bad ideas. … In Washington, if you don’t have some independence, some backbone, you might as well not even be there.”

In Wisconsin, Republican Sen. Ron Johnson has stood by his support of Trump but said in a local radio interview Friday that he may need to rely on voters splitting their tickets between him and Clinton.

“People are clearly disgusted by Secretary Clinton’s record, and if they think she’s going to actually become president, I think they’re going to start [realizing] she’s going to need somebody in the Senate to keep a pretty close watch on her and be a check and balance on her power,” Johnson said.

Toomey and Johnson currently trail in the RealClearPolitics Averages in Pennsylvania and Wisconsin by 0.4% and 3.0%, respectively.