WASHINGTON — The House unanimously agreed Saturday to provide back pay for hundreds of thousands of furloughed federal workers, but showed no sign of ending the impasse that has forced much of the government to shut down.

Lawmakers faced steep political pressure to ensure that federal workers are paid when the shutdown ends. The bill now goes to the Senate, which also convened for an unusual Saturday session, but Democrats had no immediate plans to approve the back-pay bill.

The White House has signaled that it will not veto the bill, but Democrats have largely rejected the Republican strategy of trying to reopen selective parts of government, insisting they will accept only full funding of government operations.

As the shutdown entered its fifth day, the rare weekend session in Congress offered more symbolism than substance.

The current crisis began as an attempt by tea party Republicans to stop implementation of the Affordable Care Act by withholding funding for the rest of government operations.

But the budget battle has shifted to a broader debate over the size and scope of government. Some Republicans are seeking a deal to cut Medicare, Social Security and other federal programs in exchange for funding the government and raising the nation’s debt limit by Oct. 17, the deadline for a potential financial default.

President Obama has shown little willingness to negotiate until Republicans agree to reopen the government and raise the debt limit, which is needed to ensure that the Treasury can pay obligations already made by Congress.

“This crisis could be over in hours if the speaker and Republicans would just take yes for an answer,” said House Minority Leader Nancy Pelo

Only a bill to pay military troops during the shutdown has been signed into law.