UPDATE 8-Democratic disagreements imperil Biden agenda as shutdown looms

(Adds detail on Senate vote to fund government, paragraph 4)

By David Morgan and Richard Cowan

WASHINGTON, Sept 29 (Reuters) - President Joe Biden's agenda was at risk of being derailed by divisions among his own Democrats, as moderates voiced anger on Wednesday at the idea of delaying a $1 trillion infrastructure bill ahead of a critical vote to avert a government shutdown.

The White House said talks over twin bills that would revitalize the nation's roads and airports and fund social programs and climate change measures, were at a "precarious" point as moderates and progressives disagreed over the scope of some $4 trillion in spending.

Congress, which Democrats control by a razor-thin margin, is due to vote on a bipartisan resolution to fund federal operations through early December before funding expires at midnight on Thursday.

Senate Majority Leader Chuck Schumer has scheduled votes on the measure beginning on Thursday morning, leaving plenty of time for the House of Representatives to act.

The House is also expected to vote on Thursday on a $1 trillion infrastructure bill already passed by the Senate with bipartisan support, although some party leaders warned that vote could be delayed again - which would dismay moderates.

Representative Stephanie Murphy, a moderate Democrat who backs the infrastructure bill, warned against defeat or delay of the legislation.

"If the vote were to fail tomorrow or be delayed, there would be a significant breach of trust that would slow the momentum in moving forward in delivering the Biden agenda," she told reporters on Wednesday.

With House progressives warning they will vote against the infrastructure bill until a deal is reached on the separate multitrillion-dollar plan focused on social spending and climate, the vote was not guaranteed.

"The only way the vote happens (Thursday) is if we have the votes to pass the bill," Representative Dan Kildee, House Democrats' chief deputy whip, told reporters.

WHITE HOUSE HUDDLE

House Speaker Nancy Pelosi and Schumer went to the White House on Wednesday afternoon to meet Biden, a former senator himself, who canceled a trip to Chicago to lead negotiations with Congress.

"We're obviously at a precarious and important time," White House press secretary Jen Psaki said on Wednesday.

A White House staffer met at the Capitol with moderate Democratic Senator Kyrsten Sinema, who has expressed deep concern over the size of Biden's plans and has the power to block them due to the Democrats' narrow control of the Senate.