WASHINGTON — President Joe Biden commenced a pivotal week for his presidential candidacy by addressing mounting criticism from fellow Democrats urging him to step aside from the race.

In a direct rebuttal to his detractors within the party, Biden phoned into MSNBC’s “Morning Joe” on Monday morning, asserting that he has the mandate from voters and daring those who oppose him to challenge him at the Democratic Party’s August convention.

"I’m getting so frustrated by the elites in the party... They know so much more," Biden remarked pointedly. "If any of these individuals don’t think I should run, run against me. Go ahead. Announce for president — challenge me at the convention!"

In a letter addressed to Democrats in Congress the same day, Biden acknowledged the concerns raised about his re-election bid within the party, conceding that some criticisms were made in "good faith."

"I wouldn’t be running again if I did not absolutely believe I was the best person to beat Donald Trump in 2024," Biden emphasized in the letter. "We had a Democratic nomination process and the voters have spoken clearly and decisively."

"The voters — and the voters alone — decide the nominee of the Democratic Party," he underscored.

"The question of how to move forward has been well-aired for over a week now. And it’s time for it to end. We have one job. And that is to beat Donald Trump," Biden declared. "Any weakening of resolve or lack of clarity about the task head only helps Trump and hurts us."

A senior Democratic aide confirmed the reception of Biden’s letter by congressional offices on Monday. The missive coincides with the return of both chambers of Congress from recess, marking their first session since the Biden-Trump debate in Atlanta on June 27. Biden also shared the complete letter on Instagram.

Throughout the week, Biden plans to continue outreach efforts, having already spoken with 20 lawmakers last week, including key figures like Senate Majority Leader Chuck Schumer, House Minority Leader Hakeem Jeffries, Speaker Nancy Pelosi, and Rep. James Clyburn. These conversations aim to reassure Democrats that their concerns are being heard directly from him, according to a campaign official.

On "Morning Joe," Biden dismissed concerns about prominent Democrats calling for him to exit the race, asserting, "I don’t think what those big names think... They were wrong in 2020. They were wrong in 2022 about the red wave. They’re wrong in 2024."

"I am not letting up," Biden affirmed.

Biden also took the opportunity to contrast himself with Donald Trump, framing the upcoming election as a crucial battle against extremism.

“This is a guy who’s an extreme candidate. I can’t think of a candidate in my lifetime who’s been more extreme," Biden asserted. "He makes George Wallace look like a patriot.”

In a positive development for Biden, Rep. Steven Horsford, chair of the Congressional Black Caucus, issued a statement endorsing the president on Monday.

“President Joe Biden is the nominee and has been selected by millions of voters across the country, including voters here in Nevada,” Horsford affirmed. He emphasized that voters are aware that Biden and Vice President Kamala Harris are committed to their interests.

“We’re not going back, we’re moving forward,” Horsford concluded.

As Biden navigates internal party dissent and prepares for the challenges ahead, his efforts to solidify support and portray himself as the Democratic choice to face Trump in 2024 continue to unfold against a backdrop of heightened political scrutiny and division within the party.