By Andy Sullivan

WASHINGTON (Reuters) -Republicans who control the U.S. Congress will try on Tuesday to advance legislation that would avert a weekend government shutdown, while Democrats alarmed by President Donald Trump’s dramatic downsizing effort were expected to oppose it.

The vote in the House of Representatives is likely to be close. Republicans hold the chamber by a narrow 218-214 margin, and at least one of them, Representative Thomas Massie of Kentucky, has said he will vote against it.

But Trump has been pressing his Republicans to get in line, and members who typically vote against government funding bills have said they will back this one.

If it clears the House, the legislation will also have to pass the Senate to ensure government agencies can continue operating past Friday midnight, when funding is due to expire.

Republicans in that chamber will need at least seven Democrats to vote with them to avert a lapse in funding, which could disrupt everything from financial oversight to scientific research and force hundreds of thousands of federal workers to go without pay.

Many of those workers have already been stressed by Trump’s blunt-force campaign to thin the ranks of the U.S. civil service and slash spending.

At least 100,000 of the government’s 2.3 million civilian workers have either been fired or taken a buyout so far, and Trump has effectively shuttered agencies that handle foreign aid and consumer protections. Trump’s administration has ordered a second round of layoffs as well, with plans due later this week.

Democrats say Trump’s downsizing effort, spearheaded by tech billionaire Elon Musk, runs roughshod over Congress’ authority over spending matters.

Most were expected to vote against the government spending bill, saying there would be little point in voting for legislation that will likely be ignored by Trump’s administration.

“This bill is a blank check for Elon Musk and President Trump,” Representative Rosa DeLauro of Connecticut said on Monday.

The bill would extend government funding until the end of the fiscal year on September 30, largely at current levels. Increases in defense, veterans’ care and border security would be offset by cuts to some domestic programs.

(Reporting by Andy Sullivan; Editing by Cynthia Osterman)