United States, US, President Joe Biden urged Democratic lawmakers Monday to either back his reelection campaign or challenge him at the party convention next month as the US president’s reelection bid entered a critical week.

The 81-year-old doubled down on his defiance of calls to step aside, after a disastrous debate against Republican rival Donald Trump last month turbocharged fears that he is too old to serve a second term.

Biden will be under extra scrutiny this week as he hosts a summit of NATO leaders in Washington, with many allies seeking reassurance amid polls forecasting that the isolationist Trump will win in November.

Biden called in to MSNBC’s “Morning Joe” television program to say that he was “confident” the “average voter out there still wanted Joe Biden.”

Sounding angry in the telephone interview, Biden said he was “getting so frustrated by the elites… in the party.”

“Any of these guys that don’t think I should run — run against me. announce for president, challenge me at the convention,” he added.

In a blitz of action to start the week, Biden also penned a lengthy letter to Democratic Party lawmakers that saying “I decline” to stand down.

“I am firmly committed to staying in the race,” Biden wrote.

“The question of how to move forward has been well-aired for over a week now. And it’s time for it to end.”