Nancy Pelosi (D-Calif.) will face her first challenge for House leadership since 2010 from Rep. Tim Ryan.
The Ohio Democrat announced he would challenge Pelosi for the position in a letter to lawmakers on Thursday.
"Vote for me and I will dedicate all of my energy to lead us back into the majority. Our constituents deserve nothing less,” Ryan wrote.
Ryan said it is clear that the party's current strategy is not working.
Democrats moved to postpone their leadership vote on Tuesday. The move may have signaled a growing dissatisfaction with House leadership in the wake of a sweeping Republican victory on election day.
Just weeks before the election, Pelosi had predicted Democrats would sweep the election and gain more than 20 seats in the House because Donald Trump was the "gift that keeps on giving."
Pelosi in power
Pelosi says she is confident that she will retain her position.
"Without even asking anybody for a vote, I have over two-thirds of the caucus supporting me," she said Thursday.
Who is Tim Ryan?
Ryan, 43, has represented Ohio's 13th congressional district since 2003. He serves on the House Appropriations and Budget Committees.