(CNN) Not only has Michelle Obama delivered two of the best speeches supporting Hillary Clinton during the 2016 campaign, she also provided the Democratic nominee's campaign its unofficial slogan .

"When they go low," Clinton says on the campaign trail, "We go high," her supporters shout back.

In 2008 and 2012, President Barack Obama's campaign aides anointed Michelle Obama "The Closer." This year, Hillary Clinton may well designate her most popular surrogate the starter, the reliever and the pinch-hitter, too.

On Thursday, the first lady deployed a profoundly personal rebuke of Donald Trump's sexually aggressive boasts, delivering the most powerful censure to date of the GOP candidate's cavalierly-expressed views toward women.

It was the second time this year Obama has captured her audience and driven home an emotionally-felt message in a way no other surrogate -- or, for that matter, Clinton herself -- has been able. After carefully honing an apolitical air of authenticity over the past eight years, in part by actively avoiding the harsh spotlight of campaigning, the first lady is disbursing her capital with withering force in the final 26 days before Election Day, aiming to convince the women and minority voters who helped propel the Obamas into the White House to show up one more time.

"The men that you and I know don't treat women this way," First Lady Michelle Obama told the rally.

Her voice quaking with fury, the first lady said Thursday that Trump's comments about using his celebrity to grab and grope had affected her powerfully, occupying her thoughts since the tape emerged late last week.

"I can't believe I'm saying a candidate for president of the United States has bragged about sexually assaulting women," Obama said during a campaign stop in New Hampshire.

"I've listened to this, and I feel it so personally," she said. "And I'm sure that many of you do, too -- particularly the women. The shameful comments about our bodies. The disrespect of our ambitions and intellect. The belief that you can do anything you want to a woman. That is cruel. It's frightening. And the truth is, it hurts."

The speech came only a day after the first lady marked her girls' education initiative at the White House, insisting the US should serve as a model to other countries for its treatment of young women. Her remarks on the campaign trail were as much a message to men as they were to women, amounting to a reminder that decency still exists, even as public discourse rapidly devolves.

"To dismiss this as everyday locker room talk is an insult to decent men everywhere," she said. "The men that you and I know don't treat women this way. They are loving fathers who are sickened by the thought of their daughters being exposed to this kind of vicious language about women."

Taken together with her convention speech earlier this summer , the first lady has now delivered the two most stirring addresses in support of Clinton's campaign -- and against Trump. Her now-famous utterance at the Democratic National Convention -- "when they go low, we go high" -- has become the Clinton's de facto slogan, appearing on bumper stickers and becoming the candidate's own response to Donald Trump's smears.

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"Once again, she gave a compelling and strong case about the stakes in the election, but about who we are as Americans," Clinton said later Thursday. "And we cannot let this pessimism, this dark and divisive and dangerous vision in America take hold in anybody's heart. We have to keep lifting up this campaign."

Mrs. Obama has hit the trail at a more aggressive pace than her husband, who's been constrained by a presidential schedule from making appearances more than once or twice a week. Her stops in North Carolina, Pennsylvania, New Hampshire and Virginia provide a veritable map of the areas Clinton's campaign needs to defeat Trump.

The first lady has benefited from a longtime insistence that she's not interested in seeking higher office herself, a vow that draws disappointed groans from crowds who would eagerly support another Obama campaign. A detachment from political ambition has distinguished her message from her husband, who is relying on a Democratic successor to carry on his legacy. And it separates her from Hillary Clinton, whose waded into fraught policy battles during her own term as first lady in the 1990s, and began a campaign for the US Senate before she departed the East Wing.

Michelle Obama's remarks Thursday were a divergence from the first lady's usual stump script, which is derived from the well-received convention speech she delivered in July. The race back then was a bitter slog, but hadn't yet deteriorated into the mud-fest it's become in the final stretch.

A 10-minute address that incorporated both the history-making nature of her husband's presidency and the history-making potential of Clinton's was among the best received speeches of the three-day event. Afterwards, the purple signs bearing her name were the most sought souvenir for delegates wistfully watching the Obama era end.

In her spate of appearances so far this month -- all in fiercely contested battleground states -- the First Lady has lambasted Trump for his longstanding prodding of the President about his birth place, his penchant for tweeting vitriol at the smallest perceived slights, or his complaints about his microphone at the first presidential debate.

It's a role the first lady hasn't entered lightly. Michelle Obama has spoken openly about her distaste for political vitriol and often recalls asking why her husband wanted to expose himself to the barbs of political life at all. That view was only reinforced during 2008's ugly primary battle with Clinton, to whom she's warmed after watching her service as secretary of state.

"She always had to be convinced there was a clear purpose and reason for her to go out on the campaign trail," said Kate Andersen Brower, author of "First Women: The Grace and Power of America's Modern First Ladies" who covered the Obama White House for four years.

"To see her today it's clear she was emotional, even in tears at one point. I'm not surprised the Clinton campaign didn't have to nudge her in this direction," Brower said. "I've never seen a first lady be so passionate in a speech like this before."

That ardor, Mrs. Obama said Thursday, has come as a surprise even to her.

"I can't stop thinking about this," she said. "It has shaken me to my core in a way I could not have predicted."