A Republican rebellion against Donald Trump's refusal to reopen government without new money for his Mexico border wall appears to be growing as his TV address failed to break the impasse.
Three Republican senators are now publicly calling for the government shutdown to end even if there is no border wall deal, while half a dozen more have voiced concerns about the stand-off.
Mr Trump attempted to convince his own party to stick with his strategy during a closed-door lunch with Republican senators on Capitol Hill on Wednesday.
He claimed there was "tremendous Republican support" for his stance, insisting it was his political opponents, the Democratic Party, and not his own side that was feeling the pressure.
But his blanket declaration of support clashed with the fact that some Republican politicians are beginning to break with him as the government shutdown enters its twentieth day.
Pressure will ramp up in the coming days as many of the 800,000 federal workers impacted miss out on a pay cheque for the first time since the shutdown begun. Some 25 per cent of the US federal government is affected.
Amid a fierce spin battle, a recent Reuters/Ipsos opinion poll found that 51 per cent of Americans believe Mr Trump "deserves most of the blame" for the shutdown. Just 32 percent blame congressional Democrats.
Mr Trump's prime-time address to the nation from the Oval Office on Tuesday night - his first since taking office - was full of harsh warnings about illegal immigration but broke little new ground.
The US president warned that thousands of lives would be lost if action was not taken at the border, asking: "How much more American blood must be shed before Congress does its job?"
He called the situation at the 2,000-mile long US-Mexico border a "humanitarian crisis" and urged the millions of Americans watching on to telephone their congressman and demand a border wall.
However the arguments Mr Trump deployed were the same he has been making for weeks and his central demand - that the Democrats approve $5.7 billion towards the border wall - remained unchanged.
Mr Trump notably did not declare a national emergency, something which could allow him to start wall construction without Congress's approval. Such a move would likely trigger a lengthy court battle which he is not guaranteed to win.
The US president did not rule out the move on Wednesday, telling reporters that if he fails to do a deal with the Democrats over government spending then he could still take that step.
Chuck Schumer and Nancy Pelosi, the most senior Democrats in the Senate and House of Representatives respectively, gave their own rebuttal moments after Mr Trump's speech, which lasted nine minutes and was broadcast on all major TV networks.
Ms Pelosi said: "President Trump must stop holding the American people hostage, must stop manufacturing a crisis and must reopen the government."
The Democrats were due to attend another round of talks at the White House on the shutdown yesterday. They have refused to support a spending bill with Mr Trump's $5.7 billion border wall demand included.
However the party, which now holds control of the House - one half of Congress - is planning to pass its own spending bills to reopen parts of government not linked to border security over the coming days.
By separating the Homeland Security budget from other government departments, the Democrats hope they can gain the support of moderate Republicans, putting pressure on the White House to sign such bills into law and partly end the shutdown.
That tactic appears to be working. Three Republican senators - Lisa Murkowski from Alaska, Susan Collins from Maine and Cory Gardner from Colorado - have all voiced support for the approach.
Some Republicans in the House are also expressing dissent. Adam Kinzinger, the Republican congressman for Illinois, called for the "stupid shutdown idiocy cycle" to end on Wednesday.
However the emerging rebellion has its limits, with most Republican congressmen yet to depart with the president. Mr Trump himself insisted: "The Democrats have lost support. There is tremendous Republican support. Unwavering."
Mr Trump also called illegal immigration on America's southern border "probably the world's worst problem" during a brief question-and-answer session with reporters on Wednesday.
Responding to jibes about his proposed wall - a key campaign pledge - Mr Trump said: "They say it's a medieval solution, a wall. That's true. It's medieval because it worked then and it works even better now."
If the government shutdown drags on until Saturday it will become the longest since modern records begun in 1977, according to the Congressional Research Service.