Joni Ernst had been seen as a key hurdle to Pete Hegseth’s confirmation. She approached her questions firmly but without confrontation Tuesday.

The Iowa Republican’s decision dramatically increases the likelihood that Mr. Hegseth will have enough votes to be confirmed as President-elect Donald J. Trump’s defense secretary.

Sen. Joni Ernst of Iowa, who had been seen as a key Republican skeptic of Pete Hegseth’s nomination to lead the Defense Department, said she will support him after his performance at Tuesday's confirmation hearing.