Michelle Obama has challenged men to support Kamala Harris’s bid to be 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 assault on abortion rights as the harbinger of dangerous limitations on healthcare for women.

Some men may be tempted to vote for Mr Trump because of their anger at the slow pace of progress, Mrs Obama said, but “your rage does not exist in a vacuum”.

Appearing alongside Ms Harris, she warned: “If we don’t get this election right, your wife, your daughter, your mother, we as women, will become collateral damage to your rage.

“So are you as men prepared to look into the eyes of the women and children you love and tell them you supported this assault on our safety?”

The rally in Kalamazoo was Mrs Obama’s first appearance on the campaign trail since she spoke at the Democratic National Convention over the summer, and her remarks were searing and passionate in their support of Ms Harris.

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

“Do not buy into the lies that we do not know who Kamala is or what she stands for. This is somebody who understands you, all of you.”

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

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

“I lay awake at night wondering, ‘What in the world is going on?’” she said.

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

“I am asking y’all from the core of my being to take our lives seriously,” Mrs Obama pleaded.

Ms Harris took the stage afterwards and promised the crowd that she would keep their interests in mind – unlike Mr Trump, who she accused of only being interested in himself.

“There is a yearning in our country for a president who sees the people, not just looking in the mirror all the time, but sees the people, who gets you and who will fight for you,” she said.

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

It is a level of celebrity clout that surpasses anything that Mr Trump, the Republican nominee, has been able to marshal this year. But there is no guarantee that will help Ms Harris in the close race for the White House. In 2016, Hillary Clinton lost to Mr Trump despite firing up her crowds with musical performances and Democratic allies.

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

“Kamala is at a dance party with Beyonce,” the former president said on 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 that early in-person voting became available across Michigan. More than 1.4 million ballots have already been submitted, representing 20% of registered voters.

While Ms Harris was with Mrs Obama in Michigan, President Joe Biden visited the Laborers’ International Union of North America in Pittsburgh. He mentioned that Ms Harris once walked a picket line with the United Auto Workers – “she has a backbone like a ramrod”, he said – while Mr Trump has undermined organised labour.

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

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

Speaking on Mr Trump, the president added: “I’m just gonna say straight up, he’s a loser as a man.”