WASHINGTON (Reuters) -As Republican and Democratic lawmakers trade blame for the U.S. government shutdown, some have begun to worry that the impasse is ceding their authority over federal spending to an increasingly assertive President Donald Trump.

The White House during the shutdown has frozen billions of dollars in funds meant for Democratic-led jurisdictions, sought to lay off thousands of federal workers and shifted money around to guarantee that military personnel and gun-carrying law enforcement officers will not see their pay disrupted.

Nonpartisan observers said that further marginalizes Congress at a time when Trump is already pushing the boundaries of presidential power in other areas, like military action and international trade.

"That's like an existential threat for congressional power," said Molly Reynolds, a government expert at the nonpartisan Brookings Institution think tank. "How do you negotiate a longer-term spending deal, something that goes more than just a couple of weeks, when you don't believe the executive branch is going to implement whatever choices it is that you put into that law?"

The U.S. Constitution assigns the power of the purse to Congress and not the president. Trump's fellow Republicans narrowly control both the House of Representatives and the Senate. The shutdown began on October 1, the first day of the 2026 federal fiscal year, because congressional Republicans and Democrats had failed to agree on legislation to fund government services.

Democrats have said they will not vote to resume federal funding unless Congress also addresses subsidies for 24 million Americans due to expire at the end of the calendar year. Republicans have said Congress first must pass a temporary spending bill that would allow the government to reopen.  

A Reuters/Ipsos poll found that 50% of Americans blame Republicans, while 43% blame Democrats. 

Though Democrats have framed the fight over healthcare costs, some have said they are reluctant to pass a spending bill without assurances that Trump will not simply ignore it.

"We can't do an appropriations deal and have the president then just start firing more people and cutting programs," Democratic Senator Tim Kaine of Virginia told Reuters. 

Republicans often have remained silent this year as Trump has unilaterally raised tariffs, taken military action and shifted spending, actions that typically would be the domain of Congress. Some Republicans said they understand the concerns raised by the Democrats. 

"If I were the Democrats, I'd be requiring a lot of public commitment or statutory language to be sure that it is a hard commitment," Senator Thom Tillis of North Carolina told reporters.

Democrats have focused much of their invective on White House budget director Russell Vought, chief architect of the White House funding strategy. Trump appeared to relish their consternation last week, celebrating the budget director's actions and likening him to "Star Wars" villain Darth Vader. 

Democrats also have said Trump is overstepping his authority by making sure pay is not disrupted during the shutdown for military troops and immigration and law enforcement officials, while letting other federal workers go unpaid.

"We want a bill that provides for fair payment to all of them, not just Trump's personal favorites," Democratic Senator Richard Blumenthal of Connecticut told Reuters.

With Republican House Speaker Mike Johnson keeping his chamber out of session and Senate Democrats unwilling to support a temporary spending bill, Republicans are concerned that the shutdown is preventing Congress from passing the detailed spending bills that fund government agencies for the current fiscal year. 

"It's damaging to Congress in general. We're not doing our job, and we need to start doing it," Republican Representative Mike Simpson of Montana told Reuters. "We are running out of time."

Simpson called the unilateral White House action to withhold spending unconstitutional. 

Other Republicans have said they could support legislation that would simply extend funding for a longer period and give the White House authority to determine which programs get funded.  

"We trust the president and Russ Vought to do good work if the Democrats aren't going to let us get appropriations bills done," Representative Chip Roy of Texas, a member of the ultraconservative House Freedom Caucus, told reporters.