US Democrat Nancy Pelosi delivers record-breaking eight-hour speech to push for 'Dreamers' vote

US Democratic politician Nancy Pelosi has made a record-breaking eight-hour speech aimed at securing a vote protecting so-called Dreamers - immigrants who were brought to the US as children.

The House Minority Leader, who is 77, spent much of her marathon address to the House of Representatives reading from personal letters from the 1.8 million young people whose temporary protection from deportation is set to expire next month.

"You see, these people are being deported," Pelosi said, at around the sixth hour of her speech.

"We can do something today to at least make whole the children."

She quoted the Bible and Pope Francis, and at one point interrupted herself to read a note from the House's official historian, alerting her that she had delivered the longest continuous speech to the chamber on record.

By the end, there was a quiver in her voice, a stumble over some words and a case of sniffles.

Supporters noted that she delivered the speech in four-inch heels and drank only small sips of water over the entire length of her address.

Republicans appear to have been largely unmoved by Pelosi's day-long speech, however.

But her efforts were also aimed at the liberal wing of her own party, angered after Senate Democrats cut a budget deal with Republicans that threatens to derail their attempts to secure protection for the Dreamers.

At issue are immigration protections for 1.8 million so-called Dreamers Credit: PA

The budget accord, aimed at preventing a government shutdown, is silent on the Deferred Action for Childhood Arrivals program (DACA), which shielded Dreamers but which President Donald Trump ended last year.

Immigration activists, who rallied in Washington on Wednesday during the speech, called out Pelosi and Senate Minority Leader Chuck Schumer over the deal, saying it abandons the Democrat's strategy of demanding a budget deal be paired with an immigration deal.

"What are they thinking? They're giving up their leverage," said a frustrated Angel Padilla, policy director for the liberal group Indivisible.

"All of these votes will matter come November."

Pelosi has been called out by immigration activists angry that Democrats gave up leverage on an immigration vote Credit: AP

Pelosi spoke without a break from about 10am only yielding the floor at 6.11pm.

That bests Republican Champ Clark's five-hour, 15-minute stem-winder about tariff reform in 1909.

"Honour the House of Representative and give us a chance to have a vote on the floor," she said before leaving.

She received a standing ovation from about 50 Democrats at the end of her speech, but the Republican side of the chamber was largely empty.

Pelosi's speech was not technically a filibuster - a technique sometimes deployed in the Senate to block legislation - as the rules of the House impose time limits for politicians.

But as House minority leader Pelosi is entitled to speak for as long as she wants.