Nancy Pelosi formally announces run for reelection as House speaker

In a letter to Democratic colleagues, Nancy Pelosi announced her intent to run for another two years as speaker of the House.

"Our vision for the next two years must be built on the success of [the] Democratic House Majority in the 116th Congress, and to harness the extraordinary visions, values and vibrancy of our Caucus to secure the progress that the American people deserve," she wrote in the letter sent around Thursday.

"In that spirit," she continued, "I am writing to request your support to be re-elected as Speaker."

Although Democrats were able to retain control of the House following Tuesday's vote, they did not expand their majority like the Speaker had expected prior to the election. In fact, Republicans were able to win at least five seats in the House by Friday with several still on the line.

During a conference call Thursday with House Democrats, she encouraged optimism from her colleagues.

"This has been a life-or-death fight for the very fate of our democracy. We did not win every battle, but we did win the war," she said.

"You hold your head up high," she went on to say. "We helped Joe Biden get that mandate."

In her letter, she also promised that Democrats would enact a science-based plan to "defeat" the coronavirus, as well as use its majority to improve health care and voting rights, make the economy "fairer" and fight corruption in government.

"Ours will be a government that fights for the people's interests, not special interests -- championing progress for seniors, veterans, immigrants, LGBTQ Americans, women, young people and front-line communities," she wrote.

Pelosi became the first woman elected as Speaker of the House in 2007 and she served until 2011. She was elected again in 2019.

House Democrats will formally begin the process of choosing their leaders on Nov. 18 and Pelosi isn't expected to have any challengers at this time.

ABC News' Benjamin Siegel contributed to this report.