WASHINGTON — US lawmakers negotiated behind the scenes Monday to strike a temporary agreement that would avert a potentially damaging government shutdown, with federal funding due to expire at the end of the working week.

A so-called “continuing resolution” — essentially a stop-gap deal keeping the lights on until mid-December — is likely to include more than $12 billion in military and economic aid for Ukraine.

There will also be cash for resettling Afghan refugees, boosting winter heating allowances for low-income families and providing disaster aid in flooded Jackson, Mississippi.

One roadblock however is a piece of legislation Democrats have pledged to attach to the resolution known as the Energy Independence and Security Act 2022, which has opponents on both sides of the political aisle.

The act would speed up the nation’s permitting process for energy infrastructure — both for fossil fuel projects and the clean energy initiatives championed by President Joe Biden.

But Republicans aren’t keen on handing Democrats another legislative victory with around 40 days to go until elections that will decide who controls Congress for the remainder of Biden’s first term.

Liberals are also opposed to the text, spearheaded by West Virginia Democrat and fossil fuel magnate Senator Joe Manchin, arguing that it will lead to more oil and natural gas drilling.

Manchin called on both parties to “ignore the toxic ‘all or nothing’ legislative approach that has made it hard to discern what is truly essential for our nation” in an op-ed for The Wall Street Journal on Sunday.

Although prospects for a shutdown always raise pulses as the deadline approaches — the fiscal year ends at midnight on Friday going into Saturday — analysts see such an outcome so close to the election as highly unlikely.

If the energy measure fails in a Senate vote Tuesday, analysts expect it simply to be dropped and for the main vote on government funding to go ahead without it.

House Majority Leader Steny Hoyer has warned members that the chamber will stay in session through Saturday if necessary.

Shutdowns threaten the finances of hundreds of thousands of government workers who risk being sent home without pay as parks, museums and other federal properties close.

There have been no shutdowns so far under Biden, although his predecessor Donald Trump saw two, including a 35-day shutdown from late 2018 to early 2019 that was the longest in US history.