Pennsylvania Senate candidate Kate McGinty on Tuesday pressured her rival to make a clear statement on his support for Donald Trump, seizing on the perception that the presidential nominee’s unpopularity could be a weakness for vulnerable Republicans.

Sen. Pat Toomey, who is in a dead heat with McGinty in a race that could determine the balance of power in the Senate, has not publicly endorsed Trump, but he has not ruled out supporting him. McGinty has made a point of trying to force him off balance on the issue.

“I think it is very disingenuous of Senator Toomey to not come clean with the voters in this commonwealth and tell them that he’s standing with Donald Trump,” McGinty said in a videotaped interview with The Courier Times of Bucks County. “He has said he unequivocally supports the Republican nominee. Well, that’s Donald Trump. And if he’s not supporting Donald Trump, let’s hear that, too.”

Toomey was among a handful of swing-state Republican senators to skip the party’s nominating convention — but he explained his absence with campaign obligations at home. And he has made several statements denouncing some of Trump’s more controversial statements — including Trump’s recent attacks on the parents of a Muslim soldier who died in Iraq — without mentioning Trump by name.

A Toomey spokesman, in a statement issued to the Courier Journal, pointed out that Toomey has frequently disagreed with Trump, but did not address the endorsement question.