President Joe Biden has admitted he “screwed up” in last week’s debate against Donald Trump but has vowed to continue his election campaign and reassured key allies. In an interview with a Wisconsin radio station, he acknowledged his “mistake” with his stumbling performance but urged voters to judge him based on his time in the White House.

Amid reports of uncertainty about his future, Biden moved to calm senior Democrats, including state governors and campaign staff, on Wednesday. “I’m the nominee of the Democratic Party. No one’s pushing me out. I’m not leaving,” he said during a call with the broader campaign, according to a source who spoke to news men.

Vice-President Kamala Harris, who joined Biden on the call, reiterated her support. There has been speculation about whether she could replace Biden as the party’s candidate ahead of the November election.

A fundraising email from the Biden-Harris campaign after the call was assertive. “Let me say this as clearly and simply as I can: I’m running,” Biden said.

Questions have been circulating about the 81-year-old’s campaign viability following a debate marked by verbal blanks and a weak voice, raising concerns within Democratic circles about his fitness for office and ability to win the election.

Pressure on Biden to withdraw has grown as polls indicate his Republican rival’s lead has widened. A New York Times poll conducted after the debate, published on Wednesday, showed Trump holding his largest lead yet at six points. Another poll by CBS News suggested Trump’s advantage was increasing.