UPDATE 12-Democrats delay vote on infrastructure plan, bowing to progressives

(Updates with no vote Thursday night)

By Susan Cornwell and Richard Cowan

WASHINGTON, Sept 30 (Reuters) - Democratic leaders of the U.S. House of Representatives delayed a planned vote on a $1 trillion bipartisan infrastructure bill that had been set for Thursday, bowing to party progressives who had demanded action on a larger social policy bill first.

House Speaker Nancy Pelosi and President Joe Biden have been scrambling to patch up differences between progressive lawmakers, who want a $3.5 trillion social spending package to go along with the infrastructure plan, and moderates wanting a smaller bill.

The move gave Biden and Democratic leaders more time to try to assemble the votes to gain support for a key part of his agenda.

"A great deal of progress has been made this week, and we are closer to an agreement than ever," said White House spokeswoman Jen Psaki. "But we are not there yet, and so, we will need some additional time to finish the work, starting tomorrow morning first thing."

Congress earlier on Thursday wrestled Washington back from the brink of a government shutdown by voting to continue funding the government through Dec. 3. Biden signed the measure before funding was to run out at midnight.

"There’s so much more to do. But the passage of this bill reminds us that bipartisan work is possible and it gives us time to pass longer-term funding to keep our government running and delivering for the American people," Biden said in a statement.

The House approved the measure in a bipartisan 254-175 vote, hours after it passed the Senate by 65-35.

Negotiations on the other legislation stretched into the evening. In a statement to her Democratic colleagues, Pelosi called it a "productive and crucial day" and said discussions continued.

But as the hours stretched on, it became clear no deal was apparent.

Some progressive Democrats have vowed to vote against the bill to invest in the nation's roads, bridges and other infrastructure, angry that Democrats have not yet reached agreement on a multitrillion-dollar companion bill with funding for social services and to address climate change.

Faced with increasingly stiff odds of passing their $3.5 trillion social spending proposal, Biden and his aides are trying to find out what narrower proposal could unite an ideologically fractured Democratic caucus of lawmakers, according to people familiar with the matter.

Lawmakers on the party's left flank have said they will not vote for the infrastructure bill unless they feel certain their priorities will be reflected in the social spending bill.