Michelle Obama has challenged men to back Kamala Harris’ bid to become America’s first female president, warning that women’s lives will be at risk if Donald Trump returns to the White House.

During a rally in Michigan on Saturday, the former first lady described the attack on abortion rights as a harbinger of dangerous limitations on women’s health care.

Some men might be tempted to vote for Trump because of their anger at the slow pace of progress, Mrs. Obama said, but “your anger doesn’t exist in a vacuum.”

Appearing alongside Ms Harris, she warned: “If we don’t make the right choices, your wife, your daughter, your mother, we as women will become the collateral damage of your anger.

“So are you ready as men to look the women and children you love in the eye and tell them you supported this attack on our safety?”

The Kalamazoo rally was Mrs. Obama’s first campaign appearance since speaking at the Democratic National Convention over the summer, and her remarks were fiery and passionate in support of Mrs. Harris.

“By every measure, she has shown that she is ready,” the former first lady said. “The real question is, as a country, are we ready for this moment?

“Don’t buy into the lies that we don’t know who Kamala is or what she stands for. This is someone who understands you, all of you.”

Although Mrs. Obama has been a reluctant campaigner over the years, she showed no hesitation Saturday as her speech veered from the political to the personal.

She said she fears for the country and is struggling to understand why the presidential race remains close.

“I would lie awake at night and wonder, ‘What the hell is going on?'” she said.

Her voice vibrating with emotion, Mrs. Obama spoke about women’s struggle to understand and care for their own bodies, whether it’s menstrual cycles or menopause. She spoke about the perils of childbirth, when a split-second decision can mean the difference between life and death for a mother and her baby.

“I ask you from the core of my being to take our lives seriously,” Mrs. Obama pleaded.

Ms Harris took the stage afterwards and promised the crowd she would have their best interests at heart – unlike Mr Trump, whom she accused of only being interested in himself.

“There is a desire in our country for a president who will see the people, not just look in the mirror all the time, but see the people, who will welcome you and who will fight for you,” she said.

The high-profile rally came after Ms Harris appeared with Beyonce in Houston on Friday and campaigned with former President Barack Obama and Bruce Springsteen in Atlanta on Thursday.

It’s a level of celebrity influence that surpasses anything Mr. Trump, the Republican nominee, has managed to do this year. But there is no guarantee that it will help Ms. Harris in the tight race for the White House. In 2016, Hillary Clinton lost to Mr. Trump despite firing up crowds with musical performances and Democratic allies.

Mr Trump rejected her rival’s attempt to harness star power for her campaign.

“Kamala is at a dance party with Beyonce,” the former president said Friday in Traverse City, Michigan. He held a rally in Novi, a suburb of Detroit, on Saturday before a later event in State College, Pennsylvania.

Saturday is the first day in-person early voting has become available in Michigan. More than 1.4 million ballots have already been submitted, representing 20% ​​of registered voters.

While Mrs. Harris was with Mrs. Obama in Michigan, President Joe Biden visited the Workers International Union of North America in Pittsburgh. He noted that Ms. Harris once walked the picket line with the United Auto Workers — “she has the backbone of a wand,” he said — while Mr. Trump undermined organized labor.

“He views unions as standing in the way of the accumulation of wealth for individuals,” Biden said. “It’s in the best interest of labor to beat Donald Trump, more than any other race you’ve been in.”

Mr. Biden’s remarks to the largely male audience referenced the gender gap that has been a consistent feature of this year’s presidential race.

Speaking of Mr Trump, the president added: “I’ll just say he’s a loser as a man.”