WASHINGTON - US Senate leaders said on Wednesday they had reached a bipartisan budget deal for 2018 and 2019 - a move which, if approved by Congress, would avert a second government shutdown in just three weeks.

The deal, months in the making, was seen as a major achievement for both the ruling Republicans and opposition Democrats in a deeply divided Washington.

The breakthrough came on the eve of a midnight Thursday deadline for Congress to pass a stopgap spending measure - its fifth since October - or once again turn the lights out on the federal government.

The proposal would lift caps on federal spending that were mandated under a 2011 law, boosting military and non-military funding by some $300 billion in total, aides said.

"The compromise we've reached will ensure that, for the first time in years, our armed forces will have more of the resources they need to keep America safe," Senate Majority Leader Mitch McConnell said on the Senate floor.

Republican Senator Lindsey Graham, a defense hawk, said it was the "best news for the military... since 2011".

The agreement would also ensure funding for domestic priorities pushed by Democrats including disaster relief, health centers and fighting a surging opioid epidemic.

"The budget deal doesn't have everything Democrats want, it doesn't have everything the Republicans want, but it has a great deal of what the American people want," top Senate Democrat Chuck Schumer said.

The deal raises the debt ceiling until March 2019, postponing a potential fiery clash within President Donald Trump's own Republican Party, and essentially clears the decks for Congress to address other thorny issues such as immigration and infrastructure.

Before the deal was announced, the House passed a partisan bill that would fund government for six weeks and the military through the remainder of fiscal year 2018.

The Senate is now expected to rewrite that measure, pass it and send it back for House approval before Thursday's funding deadline - provided there are no efforts to slow the process in the Senate.

Pelosi sets record

Top US House Democrat Nancy Pelosi made history on Wednesday by delivering the longest address to the chamber in at least 108 years, speaking for more than eight hours about protecting young undocumented migrants from deportation.

The veteran Democrat, who turns 78 next month, took the floor at 10:04 am and began to speak. Eight hours and seven minutes later, at 6:11 pm, she relinquished the floor - an entire work day standing at her desk in 10-centimeter heels and consuming nothing but water, according to an aide.

It was a remarkable display of determination by the minority leader and former House speaker, which ended with her high-fiving Democratic colleagues who gave her a standing ovation.

"I just got word that the House historian confirms that you have now set the record for the longest continuous speech in the House since at least 1909," said Pelosi during her marathon, reading aloud from a clerk's message.

AFP - Reuters - AP