He was disinvited from a weekend campaign event hosted by House Speaker Paul Ryan in Wisconsin, and his vice-presidential nominee, Indiana Gov. Mike Pence, refused to appear in his stead and canceled campaign events after distancing himself from the candidate.
And while pundits panned Trump's debate performance for focusing too much on personal attacks on Clinton and repeating too many already-debunked falsehoods, at watch parties in both states, Republican voters said they felt reassured.
"I think this'll change a lot of people's minds," said Orville Seymer in Milwaukee. "Hopefully the scandal will be forgotten about and we can get on to the real issues."
In Wisconsin, Republicans gathered in the back of a bar that was largely full of Packers fans watching football and cheered for Trump when he went after Clinton, roaring with laughter when he commented that the difference between Clinton and Abraham Lincoln was that "Honest Abe never lied."
In particular, Republicans in both states said they were pleased with Trump's efforts to keep Democrat Hillary Clinton on defense.
"He was more combative, but that's what we want, we want him to stand up to her," said Susan Keevican, another Pittsburgh Republican.
Red Arnold, an IT consultant from Milwaukee, praised Trump for talking about things that had been "overshadowed in the media," particularly her email use. Other supporters mentioned Trump's attacks on Clinton's role in the Benghazi attacks.
"I think a lot of things he needed to say finally got out," Arnold said.
But while they were pleased he went on the attack, they also praised Trump for largely keeping his cool while doing so, noting he did a better job of not interrupting her and staying calm than he did during his disastrous first debate performance.
"I think he was more patient than normal," said Patty Logsdon, a retiree from Milwaukee.
"[My friend] and I have spoken in the past about, he needed a zipper on his mouth — but he did well, he let her speak."
While Republican voters largely offered a glowing view of Trump's performance, they did sound one note of concern: His focus on Bill Clinton's infidelity, some voters said, distracted from the real issues.
"We still spent a lot of time of the personal stuff, that was still too much," Charlie May, a Republican at the Pittsburgh watch party, said.
"We haven't talked about visas, or people laid off at Disney world being replaced by foreign workers. We've got real issues, we've got to get off this personal stuff."
But even his critics seemed pleased with his improvement from last time.
Anthony Germaine, another Pittsburgh supporter, dismissed the initial focus on Bill Clinton's infidelities as "silliness" — but said Trump overall "did a lot better" than last time.
"He was more assertive and didn't let her get away with a lot like he did last time," Germaine said.