U.S. Senators have for a fourth time failed to pass spending proposals to reopen the federal government, extending the ongoing shutdown into next week.

Two separate spending proposals - one from the Democrats and one from Republicans - failed to reach the required 60-vote threshold.

With both sides deadlocked, the White House on Friday said it would be left with the unenviable task of mass lay-offs to keep essential government services operating if the shutdown continues, which Press Secretary Karoline Leavitt described as fiscal sanity.

The scope of those potential lay-offs remain unclear but the White House has been in discussions with the Office of Management and Budget, or OMB.

Both Republican and Democratic lawmakers have dug in their heels on the main point of disagreement: healthcare. Democrats have hoped to capitalise on the impasse to ensure health insurance subsidies for those with low-income do not expire and reverse the Trump administration's cuts to the Medicaid health programme.

Republicans, for their part, have repeatedly accused Democrats of shutting down the government in a bid to provide healthcare to undocumented immigrants - a charge that Democratic leaders have denied.

A total of 54 Senators voted in favour of a Republican-led proposal to fund the government, with 44 against and two not voting.

A separate, Democrat-led proposal also failed, with 45 voting in favour and 52 against.

Both sides have continued to blame the other for the shutdown, with little sign of any progress in negotiations.

During a news briefing at the White House, Press Secretary Karoline Leavitt accused Democrats of holding Americans hostage over their demands.

White House officials have repeatedly vowed to lay off federal workers if the shutdown continues, asserting that $15 billion in GDP could be lost each week as unemployment rises.

As part of the federal government's response to the shutdown, Vought announced the suspension of $2.1 billion in federal infrastructure funding for Chicago, in addition to previous freezes of $18 billion in New York City and cancellations of approximately $8 billion in funding for federal energy projects in Democratic-run states.

On the Senate floor, Minority Leader Chuck Schumer stated that Democrats are fighting the healthcare issue because we know Americans want this.

Some Democrats have expressed the need to hear directly from President Trump about the ongoing stalemate, with concerns that compromises with Senate Republicans may be undermined by the president.

Polls indicate that public opinion is divided, with significant numbers of Americans blaming Republicans for the shutdown.