WASHINGTON (AP) — Joe Biden's campaign said Monday that the presumptive Democratic nominee would commit to participating in three debates, and slammed a push by President Trump's advisers for an additional debate as an "effort to change the subject."

"Our position is straightforward and clear: Joe Biden will accept the Commission's debates, on the Commission's dates, under the Commission's established format and the Commission's independent choice of moderators," said Biden Campaign Manager Jen O'Malley Dillon in a letter to the Commission on Presidential Debates, the nonprofit group that sponsors general election debates, which was obtained by The Associated Press. "Donald Trump and Mike Pence should do the same."

"Any 'debate proposals' in lieu of that are just an effort to change the subject, avoid debates, or create a distracting 'debate about debates,'" she added.

The letter, which was first reported by The Washington Post, came in response to a request made by Trump campaign manager Brad Parscale and former New York City Mayor Rudy Giuliani to add another, earlier debate to the current schedule of three. They also proposed that each campaign have a role in selecting the debate moderators.

Trump's team noted absentee and mail voting is being expanded because of the COVID-19 pandemic and expressed concern that some ballots — especially those by elderly voters most at risk to the virus — could be cast before the first debate. The first is scheduled for Sept. 29 at the University of Notre Dame in Indiana, the second on October 15 at the Adrienne Arsht Center for the Performing Arts of Miami-Dade County in Miami (it was previously scheduled to be held at the University of Michigan in Ann Arbor) and the third for a week later, Oct. 22, at Belmont University in Nashville.

The seeming acceptance that a vast number of this year's votes will be cast by mail marks a change for the campaign. Both Giuliani and Trump have criticized widespread mail voting and claimed without evidence that mail ballots are ripe for fraud.

In the Monday letter, O'Malley Dillon also pointed out that the Trump campaign's request for more debates marked a shift from December, when advisers were threatening that Trump might skip the debates altogether.

That shift comes as Trump's campaign has been seeking to paint Biden as mentally unsuited for the presidency, pointing to some of his verbal flubs on the campaign trail and lambasting the former vice president for campaigning "from his basement" during the pandemic, as Trump hit the campaign trail for his first rally during the pandemic this past weekend.

Indeed, in a statement on the Biden campaign's refusal to engage in additional debates, Trump campaign communications director Tim Murtaugh charged that his aides were "afraid" to send the Democrat out in unscripted situations, noting it's been more than 80 days since Biden held a press conference.

"An earlier and longer debate schedule is necessary so Americans can see the clear difference between President Trump's vibrant leadership and Biden's confused meandering," he said.

In the Monday letter, O'Malley also asked that the CPD confirm that it's formulating safety plans to ensure that the debates will go on despite the coronavirus pandemic, and that the second debate be held in a town hall format, which would allow voters to ask questions of each candidate.

"The Trump campaign proposal for elaborate negotiations is merely an effort to dodge fair, even-handed debates," O'Malley Dillon wrote.