Seth Moulton (D., Mass.) and Tim Ryan (D., Ohio) for Rep. Marcia Fudge (D., Ohio) to challenge Pelosi for speaker.
Pelosi allies were quick to jump on the letter Monday as proof that Pelosi will overcome the challenges.
However, more than two dozen Democratic representatives who will be in the House when the next Congress starts in January have expressed reluctance over supporting Pelosi.
On the other, Pelosi's critics say she has become such a weight on the party, starring as the chief villain in Republican attack ads against Democrats, that she needs to step aside and make way for a new generation of leadership. If Democrats stay at 232 seats, she can only afford to lose 14 votes.
"Our majority came on the backs of candidates who said that they would support new leadership because voters in hard-won districts, and across the country, want to see real change in Washington". Two of them - Anthony Brindisi of NY and Ben McAdams of Utah - are in races in which The Associated Press has yet to call a victor. One of the letter-signers may not even make it to Congress - Democrat Ben McAdams now trails Rep. Mia Love in a too-close-to-call race in Utah.
The former Clinton Cabinet official said Pelosi has earned the right to the speakership, at least for now.
Those opposing Pelosi's candidacy say that this type of whip operation is exactly why they need new leadership, arguing that the new members who campaigned against her are now finding themselves pressured to cast a vote that could ultimately cost them reelection.
But also missing from the letter were the signatures of Representative Conor Lamb and four newly elected Democrats - all of whom had pledged to support efforts to displace Pelosi on the campaign trail.
"We promised to change the status quo, and we intend to deliver on that promise", the letter continued.
Trump has tweeted his respect for Pelosi and offered to round up GOP votes to help elect her speaker. "She has probably the most diverse leadership team in the history of any legislative body as far as the Congress is concerned", Rep. Elijah Cummings, D-Md., the incoming House Oversight Committee chairman and a CBC member, said on CBS News' "Face the Nation". It also includes Ben McAdams, who not only hasn't won, but is trailing. She's likely to overcome such a threshold, depending on how large the Democratic majority shakes out to be.
"We'll see how it plays out a lot of people haven't made their decisions yet", said Moulton.
"Leader Pelosi remains confident in her support", said spokesman Drew Hammill.
Another signer, Rep. Ed Perlmutter of Colorado, told reporters earlier this month that he may not be a firm "no" vote on Pelosi. She said last week that she wouldn't need Republican votes and taunted Fudge about potentially running. The letter was initially supposed to be released last week. "You better think about that long and hard".
"She's a very wealthy person".