President Donald Trump marked the first anniversary of his inauguration Saturday with his government in shutdown, accusing Democrats of taking Americans hostage with their demands.

From midnight Friday, in the absence of an agreed spending plan, federal services began to come to a halt or be scaled back, even as lawmakers continued to argue on the floor of the Senate.

Essential services and military activity will continue but many public sector workers will be sent home without wages and even serving soldiers will not be paid until a deal is reached to reopen the US government.

A deal to avert the shutdown had appeared likely earlier Friday, when Trump seemed to be close to an agreement with Democratic Senate minority leader Chuck Schumer on a measure to prevent the expulsion of undocumented migrants who arrived in the country as children.

But no such compromise was in the language that reached Congress for a stop-gap motion to keep the government open for four more weeks while a final arrangement is discussed -- and Republicans failed to win enough Democratic support to bring it to a vote.

The White House lashed out at Schumer, blaming him for the shutdown and doubling down: Trump's spokeswoman Sarah Sanders declared that he would never negotiate an immigration deal at all until Congress agrees to resume normal government spending.

"Senate Democrats own the Schumer Shutdown," she declared.

"Tonight, they put politics above our national security, military families, vulnerable children, and our country's ability to serve all Americans.

"We will not negotiate the status of unlawful immigrants while Democrats hold our lawful citizens hostage over their reckless demands," she said.

Republican majority leader Mitch McConnell echoed the White House's language, but Schumer fought back, blaming Trump for leading him to believe a deal was possible on the immigration dispute but then failing to bring his own party along.

Responsibility to govern

"Every American knows the Republican Party controls White House, the Senate, the House — it is their job to keep the government open. It is their job to work with us to move forward," Schumer told the Senate, after the 50 to 49 vote.

"They control every ounce of the process and it is their responsibility to govern and here they have failed," he declared.

Democrats accused Republicans of poisoning chances of a deal and pandering to Trump's populist base by refusing to fund a program that protects 700,000 "Dreamers" — undocumented immigrants who arrived in the US as children — from deportation.

The president shelved plans to fly to Florida to celebrate at his Mar-a-Lago estate the first anniversary of his inauguration to remain in Washington to ride out the storm.

Republicans have a tenuous one-seat majority in the Senate but would have needed to lure some Democrats to their side to get a 60 vote supermajority to bring the motion forward. They fell ten votes short.

The measure brought to Congress would have extended federal funding until February 16 and reauthorized for six years a health insurance program for poor children -- a long-time Democratic objective.

But it would have cut the Deferred Action on Childhood Arrivals program, known as DACA, that affects Dreamers.

White House officials insisted there was no urgency to fix DACA, which expires March 5.

With mid-term congressional elections looming later this year, Republicans risk being blamed by voters when the government stops functioning over lack of funds.

A new Washington Post/ABC poll found that 48 percent of Americans blame Trump and the Republicans for a potential shutdown, and only 28 percent hold Democrats responsible.

There have been four government shutdowns since 1990. In the last one in 2013, more than 800,000 government workers were put on temporary leave.

International ratings agency Fitch said a partial shutdown was unlikely to affect America's AAA/stable rating for US sovereign debt.

Negotiations with the White House on a bipartisan compromise on DACA blew up last week after Trump reportedly referred to African nations and Haiti as "shithole countries."

Trump's unpredictable Twitter outbursts and sudden changes of position also have bedevilled Republican leaders as they maneuver to cut a deal.