House Minority Leader Nancy Pelosi, D-Calif., announced Wednesday evening that she had agreed to serve no more than four more years as leader of the chamber's Democrats under an agreement with party insurgents, virtually ensuring that she will be elected Speaker of the House when the new Congress convenes next month.

Under the terms of the agreement, House Democratic leaders will be limited to three two-year terms, though each could serve an additional term if two-thirds of the caucus support the leader staying in office. The agreement is retroactive to include the four years that Democrats held the House majority between 2007 and 2011.

In a statement, Pelosi said the proposed agreement would be put to a vote by Feb. 15. However, she added: "I am comfortable with the proposal and it is my intention to abide by it whether it passes or not."

The plan represents a narrowing of a package Democrats had considered that also would have restricted the number of years that lawmakers could serve as House committee chairs. The idea of curbing the power of seniority has encountered blistering criticism from long-time lawmakers and members of the Congressional Black Caucus, several of whose members are in line to lead committees.

Democratic members who oppose Pelosi told Fox News earlier Wednesday the prospective plan would protect the current caucus leadership rather than infusing it with new blood. However, Rep. Tim Ryan, D-Ohio, who challenged Pelosi for the leadership in 2016, endorsed the agreement, calling it "a historic step" toward "creating a system that will ensure the speedy rise of new leadership reflecting the diversity and energy of our caucus."

Six other Democrats who had opposed Pelosi's return to the speakership joined Ryan in a statement vowing to "support and vote for Nancy Pelosi for Speaker."

"We wish to thank Nancy Pelosi for her willingness to work with us to reach this agreement," read the statement from Ed Perlmutter, D-Colo.; Bill Foster, D-Ill.; Linda Sanchez, D-Calif.; Seth Moulton, D-Mass.; Ryan; Filemon Vela, D-Texas; and Rep.-elect Gil Cisneros, D-Calif. "We are proud that our agreement will strengthen our caucus and will help develop the next generation of Democratic leaders."

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Pelosi was the heavy favorite to become House Speaker for a second time after Democrats won at least 235 House seats -- pending the final outcome of a disputed election in a North Carolina district -- in last month's midterm elections, but some Democrats had called for change at the top of the caucus.

Party rebels have said it's time for Pelosi and her two top lieutenants, No. 2 leader Steny Hoyer of Maryland and No. 3 leader Jim Clyburn of South Carolina, to step aside and make room for a new generation. Pelosi, 78, and Hoyer, 79, have served as the top two House Democrats since 2003, while Clyburn, 78, has been the third-ranking Democrat since 2011.

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Rep. Cedric Richmond, D-La., the Congressional Black Caucus chairman, criticized the proposal. He said party leaders are "people who've earned it" and added, "I don't see what problem we're trying to fix."

Democrats said they would consider whether to clamp term limits on committee chairs early next year.

The Associated Press contributed to this report.