WASHINGTON — And then there were none.

A Democratic insurgency seeking to force Representative Nancy Pelosi to abandon her bid for speaker and install a fresh crop of leaders at the helm of their new majority suffered a setback on Tuesday, when Representative Marcia L. Fudge, the sole lawmaker to flirt openly with a challenge, dropped the idea and endorsed her.

Ms. Fudge’s sudden reversal was the result of a swift and relentless bit of deal-cutting by Ms. Pelosi, a legendary negotiator and vote-counter who has insisted that she will have the support to claim the speaker’s gavel despite a rebellion in Democratic ranks.

It sent a group of dissidents who released a letter on Monday calling for new leadership back to the drawing board to find a Democrat willing to directly challenge Ms. Pelosi, 78, who has led her party for 15 years, handily dispatching would-be challengers along the way.

Ms. Fudge, who is African-American, said she had changed her mind after Ms. Pelosi gave her the opportunity to play a key role in safeguarding voting rights and assured her that black women would “have a seat at the decision-making table” in the new Congress.