Hillary Clinton came out swinging against Donald Trump today after the first presidential debate of the general-election season, criticizing his post-performance gripes, questioning his wealth and suggesting a "strong probability" the GOP nominee has not paid federal income taxes in years.

"He actually bragged about gaming the system to get out of paying his fair share of taxes," Clinton said while campaigning in North Carolina today, referring to an exchange from Monday night's debate. "In fact, I think there's a strong probability he hasn't paid federal taxes a lot of years."

She added, "When I confronted him with the reasons why he won't release his tax returns and I got to that point where I said, 'Well, maybe he's paid zero,' he said that makes him smart. Now, if not paying taxes makes him smart, what does that make all the rest of us?"

Clinton, who took several days off the campaign trail to prepare for the candidates' first face-off, also said her opponent was ill-prepared.

"He made it very clear that he didn't prepare for that debate," she told the crowd of roughly 1,400. "At one point he was kind of digging me for spending time off the campaign trail to get prepared. But just trying to keep track of everything he says took a lot of time and effort."

Trump called in to "Fox & Friends" this morning, at one point saying he thought he had microphone issues during Monday night's debate. But he later said it must have been working well enough to pick up his breathing when it sounded as if he was sniffling.

Clinton reacted this morning aboard her campaign plane, saying, "Anyone who complains about the microphone is not having a good night."

Asked by reporters whether she thinks Trump will skip the remaining two debates next month — as he and some of his surrogates have suggested — she said she'll be there, no matter what.

"Well, I'm going to show up. He gets to decide what he's going to do," Clinton said. "But I will be there in St. Louis and then after that in Las Vegas.

She added, "If I'm the only person onstage, well, you know, I'm the only person onstage."

At her campaign event in Raleigh, North Carolina, today Clinton took a veiled swipe at Trump's wealth.

"One of my guests was Mark Cuban," Clinton said, referring to him as "a real billionaire."