Since the Democratic convention, where her speech on the first night was widely regarded as perhaps the highlight of the four-day gathering, Michelle Obama has emerged as one of Hillary Clinton's top surrogates, as she's cast Clinton's GOP opponent, Donald Trump, as unfit to be a moral leader for the nation.

At a campaign event Thursday, the first lady again took on the Republican presidential nominee, reacting to his latest, perhaps most explosive controversy yet: the recently released 2005 recording in which he's heard graphically discussing groping women, which was followed this week by accusations from multiple women that he'd made unwanted sexual advances toward them, which he has denied.

"Last week, we saw this candidate actually bragging about sexually assaulting women," the first lady said in Manchester, N.H, "and I can't believe that I'm saying that a candidate for president of the United States has bragged about sexually assaulting women."

She continued: "I can't stop thinking about this. It has shaken me to my core in a way that I couldn't have predicted."

During her July convention speech in Philadelphia, Obama, without naming him, asserted that Trump was unfit to fulfill the role of national role model.

"This election, and every election, is about who will have the power to shape our children for the next four or eight years of their lives," the first lady said. "And I am here tonight because in this election, there is only one person who I trust with that responsibility, only one person who I believe is truly qualified to be president of the United States, and that is our friend, Hillary Clinton."

On Thursday, the first lady said it would be "dishonest" and "disingenuous" for her "to just move on to the next thing like this was all just a bad dream."

"It's not something we can just sweep under the rug as just another disturbing footnote in a sad election season," she added of the Trump revelations.

The first lady also, as she did in Philadelphia, laid out what she said were the stakes for American children.

“In our hearts, we all know that if we let Hillary’s opponent win in this election, that we are sending a clear message to our kids: that everything they’re seeing and hearing is perfectly OK," she said.

"We're telling our sons that it's OK to humiliate women," the first lady said. "We're telling our daughters that this is how they deserve to be treated. We're telling all our kids that bigotry and bullying are perfectly acceptable in the leader of their country.

"Is that what we want for our children?" Obama asked.