President Joe Biden pledged Monday to stay in his race for reelection, even after a weekend in which a growing number of Democrats asked for him to withdraw and a key U.S. House Republican called for an investigation into the president’s doctor.

In a letter to congressional Democrats, Biden argued that the calls for him to drop out of the presidential race — with just 119 days until Election Day — ignored the results of Democratic primaries and caucuses that he handily won and said he remained the best candidate to defeat former President Donald Trump.

The two-page letter ended with a call for party unity and an end to the public back-and-forth among Democrats over whether Biden should leave the race, after a June 27 debate performance that shook some high-ranking Democrats’ confidence in his ability to overcome his polling deficit against Trump.

“The question of how to move forward has been well-aired for over a week now,” Biden wrote. “And it’s time for it to end. We have one job. And that is to beat Donald Trump.”

Comer seeks interview with Biden doctor

Congress returns Monday from a weeklong July Fourth recess after several days in which members of both parties continued to press the issue of Biden’s fitness for office.

Republicans also began pressing for more details. House Oversight and Accountability Chair James Comer on Sunday called for Biden’s physician, Dr. Kevin O’Connor, to submit to a transcribed interview about his assessments of Biden and O’Connor’s business dealings with James Biden, the president’s brother.

The Kentucky Republican said Biden and the White House had sent mixed messages about recent medical examinations of the president.

White House press secretary Karine Jean-Pierre told reporters last week that Biden had not been examined by a doctor since his regular checkup in February.

But Biden told a group of Democratic governors the same day that he was “checked out by a doctor” following the debate, Comer wrote.

Following the debate, Biden, attempting to explain a low, raspy voice, said he’d had a cold.

Comer also questioned if O’Connor could accurately report Biden’s health, or if he was compromised by a conflict of interest because of his involvement with James Biden’s rural health care company, Americore. James Biden has testified to the committee that he sought O’Connor’s counsel for the business.

The White House did not respond to a message seeking comment about Comer’s request.

More Democrats call for withdrawal

The holiday weekend also saw more U.S. House Democrats join a list of those asking Biden to step aside rather than seek reelection.

In a written statement on Saturday, Minnesota’s Angie Craig became the first member from a competitive district to call on the president to quit the race. Craig is the fifth member to publicly call for the president’s withdrawal.

Additional members are making private calls, according to media reports.

Four Democrats who lead House committees — Jerry Nadler of New York on the Judiciary Committee, Adam Smith of Washington on the Armed Services Committee, Mark Takano of California on the Veterans’ Affairs Committee and Joe Morelle of New York on the House Administration Committee — said during a caucus leadership call on Sunday that Biden should withdraw, according to reports.

Other accounts reported more members on the call, including Susan Wild of Pennsylvania and Jim Himes of Connecticut, also opposed Biden’s continued candidacy. Wild later told the Pennsylvania Capital-Star she expressed concerns about Biden’s electability.

In an impromptu call in to the MSNBC show “Morning Joe” on Monday, Biden insisted again he was staying in the race and called for any opponents he had to “challenge” him at the party’s convention in Chicago next month.

Biden, who has secured enough pledged delegates through primary and caucus wins to clinch the nomination, would be heavily favored in a contested convention. Democratic Party rules mandate pledged delegates “shall in all good conscience reflect the sentiments of those who elected them,” but are not legally required to cast their convention vote for their pledged candidate.