WASHINGTON (Reuters) - The Republican-controlled U.S. House of Representatives and Democratic-majority Senate on Friday will scramble to beat a midnight government shutdown deadline by passing a $1.2 trillion bill keeping the government funded through September.

If they succeed, it will end a more-than-six-month battle over the scope of Washington's spending for the fiscal year that began Oct. 1. If they fail, federal agencies will begin a partial shutdown, furloughing thousands of workers nationwide and abroad.

"This bill funds our highest national security priorities," Republican House Appropriations Committee Chairwoman Kay Granger said in a statement on Thursday, praising the bipartisan deal.

Granger mainly was referring to the Defense Department's $886 billion in funding included in the 1,012-page bill that also covers agencies ranging from the Department of Homeland Security, Internal Revenue Service and Justice Department to Treasury and State departments.

It will add to the fast-growing national debt that now totals nearly $34.6 trillion.

Not all Republicans were as enthusiastic over the bill.

Representative Robert Aderholt, who chairs a House appropriations subcommittee, raised concerns about the prospects for passage by voicing opposition to the measure over provisions that he said would benefit undocumented immigrants and fund abortion services.

"I cannot and will not vote for these projects or this bill," Aderholt said in a statement.

The hardline House Freedom Caucus, which represents roughly three-dozen Republicans, also complained that the bill is loaded with "radioactive 'woke' earmarks."

Earmarks are special spending requests sought by individual members of Congress, often public works projects for their home states or districts.

Still to be seen is whether conservative Republicans in the Senate delay passage of the bill by demanding debate on a series of amendments.

A separate controversial money matter is boiling in Congress where its leaders, except for House Speaker Mike Johnson, urgently are calling for final passage of a $95 billion security assistance package approved by the Senate for Ukraine, Israel and Taiwan.

Some Republicans are balking at continuing to back Ukraine in its war against the invading Russian military.

While conservatives succeeded in getting Congress and Democratic President Joe Biden to agree to some fiscal 2024 spending cuts, they hoped for far deeper ones. Their disgruntlement led to the historic October removal of House Speaker Kevin McCarthy. The Republicans' subsequent political infighting shut down the House for three weeks as Republicans fought over a replacement.

BACK TO THE BRINK

Since then, with the November elections looming, most Republicans have been loath to trigger a government shutdown over spending, although Washington was brought to the brink four times since late September.

The last shutdown occurred during Donald Trump's presidency, from Dec. 22, 2018 until Jan. 25, 2019. The record-long interruption in government services came as Trump insisted on money to build a wall along the U.S. border with Mexico and was unable to broker a deal with Democrats.

It ended when some air traffic controllers in major airport hubs, tired of working without pay, threatened to stay at home.

Rating agencies have warned that the repeated brinkmanship could take a toll on the U.S. government's creditworthiness.

A shutdown beginning on Saturday would mean most U.S. Border Patrol and immigration agents would continue to work. But local governments might not receive new aid to shelter migrants.

U.S. soldiers and all federal workers would not get paid until new funding is enacted and national parks would be shuttered. Same situation for the two U.S. astronauts aboard the International Space Station 254 miles (409 km) above Earth.

Meanwhile, the Internal Revenue Service would continue processing tax returns that are due on April 15. It would advise taxpayers of any potential delays in refunds. At the State Department, security at embassies and other foreign offices would remain in force and passports and visas would be issued as long as there were sufficient fees to support such activities. Many other operations would cease.