Doug Emhoff has expressed regret over an affair he had during his previous marriage, after media reports claimed he had a relationship with his children's nanny.
Kamala Harris’s husband said he had caused his family “some tough times” after being unfaithful to his first wife, Kerstin.
Emhoff’s past relationships have been put under the spotlight since his wife entered the race to be president.
In a statement issued to CNN Emhoff, who is Jewish and could become the America’s first First Gentleman, explained: “During my first marriage, Kerstin and I went through some tough times on account of my actions.
“I took responsibility, and in the years since, we worked through things as a family and have come out stronger on the other side.”
The Daily Mail first reported that Emhoff’s marriage to Kerstin broke down when he allegedly got the nanny pregnant.
He has not commented on this allegation directly but according to a source in the Daily Mail the nanny “did not keep the child”.
His marriage of 16 years ended when Kerstin learned of the affair in 2009.
At the time their daughter, Ella, was 10, and son, Cole, was 15.
According to the Mail, Harris, who married Emhoff in 2014, has always known about the affair.
Brian Fallon, a spokesman for the Harris campaign, told CNN that he would not comment beyond the statement Emhoff had released.
Despite the past struggles in their relationship, Kerstin has shown significant public support for her ex husband and his new wife, the vice-president.
She has hit back at criticism of Harris for having no children and described her as “co-parent” of their children.
On Saturday she said: “Doug and I decided to end our marriage for a variety of reasons, many years ago.
“He is a great father to our kids, continues to be a great friend to me and I am really proud of the warm and supportive blended family Doug, Kamala and I have built together.”