At 78 years old, Nancy Pelosi remains the only woman to have ever been the Speaker of the House of Representatives.

She has now reclaimed the gavel, after a vote of 220 to 192, to once more become the highest-ranking female politician in American history.

"Nancy Pelosi is a woman of faith, a loving wife, a mother of five, a grandmother of nine, a sophisticated strategist, a legendary legislator, a voice for the voiceless," Representative Hakeem Jeffries, the incoming Democratic caucus chair, said after she was elected.

"Let me be clear, House Democrats are down with NDP, Nancy D'Alesandro Pelosi, the once and future speaker of the House of Representatives."

A 'sophisticated strategist and legendary legislator'

Despite serving as House leader for 16 years, Ms Pelosi faced internal opposition from long-time critics as well as challengers. ( Facebook: Nancy Pelosi )

Ms Pelosi was first elected to Congress in 1987 and served as speaker from 2007 to 2011.

Among her accomplishments in the role is the passing of a number of landmark bills — such as the Affordable Care Act and the American Recovery and Reinvestment Act, which helped get the United States out of the Great Recession.

She was a fierce critic of George W Bush's plans to increase troop levels in the Iraq war, opposed President Donald Trump's tax reform and was the driving force behind the Fair Minimum Wage Act of 2007, which raised the US minimum wage.

She's also served as the House minority whip, becoming the first woman in US history to hold that post as well.

On top of that, she holds the record for longest House speech, having staged the eight-hour marathon filibuster last year in a bid to try and force a vote on the Dreamers program.

Sorry, this video has expired Nancy Pelosi's speech was the longest in the House on record (Photo: Reuters/US House TV)

'She'll cut your head off and you won't even know you're bleeding'

It's a level of determination that might serve her well in the next few days, as she confronts her first challenge as Speaker: the US government shutdown and a battle over Donald Trump's wall.

Ms Pelosi — along with Senate Democratic Leader Charles Schumer of New York — have already laid responsibility for the impasse at Mr Trump's feet, having previously called it a "Trump shutdown".

She even reportedly commented that the border must be a "manhood thing" for Mr Trump

"We're not doing a wall. Does anybody have any doubt that we are not doing a wall? So that's that," she said at a news conference.

It's not the first time she's clashed with Mr Trump, Ms Pelosi has also fought him on issues including the DACA program. In response, Mr Trump has called her "high-tax, high-crime Nancy Pelosi".

But that dynamic may shift now that Ms Pelosi holds power over Mr Trump.

As Democratic speaker for the House, she will oversee a sweeping series of investigations of the US President, his business interests and the first two years of his presidency.

She's already declined to rule out impeachment, and if the words of her filmmaker daughter are anything to go by, she's going to prove a tough opponent for Mr Trump.

"How does she approach meetings with President Trump, A, and B, just what are your feelings about this person who you know quite well becoming Speaker of the House for a second time?" host John Berman asked her during an interview on CNN's New Day.

Alexandra Pelosi responded: "She'll cut your head off and you won't even know you're bleeding."

She went on to warn that "no-one has ever won betting against Nancy Pelosi".

But she faced a rebellion from within her own party

Despite serving as House leader for 16 years, Ms Pelosi faced internal opposition from long-time critics as well as challengers who publicly stated during their campaigns they would not back her for speaker.

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Under her leadership, Democrats gained 40 seats in November's elections, giving them House control after eight years in the minority.

But it was not enough to stop the rebellion from Democrat representatives — including Tim Ryan of Ohio, Kathleen Rice of New York and Seth Moulton of Massachusetts — who called for younger, fresh leaders.

At one point, she was labelled by one Democrat as more toxic than Mr Trump in some areas of the country.

The rebel Democrats also said that years of Republican advertising which has portrayed Ms Pelosi as an "out-of-touch radical" had hurt Democrats' chances to win in moderate districts.

Despite the rebels believing they had enough support, Ms Pelosi was able to secure the top job after weeks of one-on-one meetings, promised committee assignments and legislative priorities and lobbying by outside prominent Democrats and groups.

She was so successful at arguing her case, eight of 16 Democrats who signed a letter in November saying they were "committed to voting for new leadership" ended up backing Ms Pelosi, including Mr Ryan and Mr Moulton.

She secured the role after promising to serve no more than four additional years as speaker.

ABC/wires