When Nancy Pelosi was elected Speaker of the U.S. House of Representatives in 2007, she became the first woman to ever serve in that role. And with Democrats regaining the majority in Congress after the midterm elections, she's poised to get her old job back.

House Democrats officially nominated Pelosi, 78, to lead them in the new Congress on Nov. 28. She ran unopposed as the nominee despite unrest from those in her party clamoring for new leadership and is expected to retake the gavel Thursday.

In accepting her old post again, Pelosi will give a nod to the new era of divided government with a pledge to "reach across the aisle in this chamber and across the divisions in this great nation," according to excerpts of her prepared remarks.

Although she won't be the first Speaker to take back the role, the last time a lawmaker regained the gavel was more than a half-century ago.

What is the role?

The Speaker is in charge of three types of duties – institutional, representative and party leader – according to the Office of the Clerk of the U.S. House.

Institutional: The Speaker acts as the presiding officer and administration head of the House.

Representative: The Speaker acts as an elected member of the House.

Party Leader: The Speaker acts as the leader of the majority party in the House.

The Speaker is tasked with nominating chairs and members for the Rules Committee and House Administration Committee. He or she also appoints speakers pro tempore and members for joint House and Senate conference committees and acts as a liaison to the president and the Senate.

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Additionally, the House Speaker is in line after the vice president to succeed the president if necessary.

Didn’t she do this before?

She did – and was the first woman to hold the position when she was elected in 2007.

Pelosi has served in Congress since 1987. She was the Speaker from 2007 to 2011. Currently, Pelosi is the House Minority Leader, a position she’s held since 2011.

How many votes does she need?

Article 1, Section 2 of the Constitution gives Congress the ability to select their own Speaker. It does not, however, mandate that the Speaker has to be a member of Congress – although historically that has been the case.

As the new Congress convenes – with Democrats in the majority – members will hold a vote on the next Speaker. Each party will be able to nominate a candidate, and lawmakers will cast their votes by a roll call vote, the Office of the Clerk explains. The roll call vote is repeated until someone receives a majority.

To get the gavel, Pelosi needs to win an “absolute majority” of votes cast on the House floor. She was officially nominated for the role by House Democrats on Nov. 28.

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The longest election for Speaker lasted two months and took 133 ballots in 1856, according to the U.S. House archives. Then, Rep. Nathaniel P. Banks of Massachusetts emerged victoriously.

Who's opposing her?

Pelosi faced opposition from several in her own party in her bid for Speaker who said it was time for a new generation to take the helm. Those Democrats tired of the many Republican attack ads featuring Pelosi constantly run against them back home and worried she would be a drag on efforts to keep the majority in the next election.

Those Democrats enlisted some of the newcomers from the freshmen class to their ranks.

Ahead of her nomination, 16 House Democrats circulated a letter calling for “new leadership” and promising to vote against her, although a couple lawmakers have seemingly walked back that pledge.

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But over time, Pelosi began to win over the skeptic lawmakers, flipping "no" votes to the "yes" column, sometimes in a matter of days. Some were given lead positions on their legislative priorities, even a gavel of their own to chair special panels.

And Pelosi gave a little, too, promising to serve no more than four years in leadership, making way for the next generation.

Has Trump weighed in?

Trump has tweeted multiple times his supposed support for Pelosi for Speaker.

“In all fairness, Nancy Pelosi deserves to be chosen Speaker of the House by the Democrats. If they give her a hard time, perhaps we will add some Republican votes,” Trump said on Nov. 7. “She has earned this great honor!”

“I can get Nancy Pelosi as many votes as she wants in order for her to be Speaker of the House. She deserves this victory, she has earned it - but there are those in her party who are trying to take it away. She will win!” Trump said again on Nov. 17.

The Associated Press contributed to this report.