A US senator has said she turned down Donald Trump’s request to run as his vice president in 2016 because of family concerns.

Joni Ernst, who represents Iowa, made the claim in an affidavit in a divorce proceeding that was first reported by Cityview, a Des Moines alternative newspaper.

The filing was made in October but unsealed this month after Ms Ernst and her former husband, Gail Ernst, settled their previously contentious divorce.

Ms Ernst wrote that, after Mr Trump interviewed her in July 2016 to be his running mate: “I turned Candidate Trump down, knowing it wasn’t the right thing for me or my family.”

She said it was a sacrifice she made for her husband, who was not fond of her political career.

Joni Ernst Divorce
Then vice president Joe Biden administers the Senate oath to Senator Joni Ernst, with her then husband Gail Ernst and daughter Elizabeth in 2015 (Jacquelyn Martin/AP)

Mr Trump eventually invited Mike Pence, then the governor of Indiana, to run with him and Mr Pence now holds the vice-presidency.

Ms Ernst has indicated she will run for a second six-year Senate term in 2020.

The White House and Trump campaign did not immediately respond to requests for comment.