President Donald Trump has rejected a Republican call for temporarily reopening US government agencies to encourage talks with Democrats over border security issues, as a partial government shutdown limped through its 24th day.
About one-quarter of federal government operations have been shut down by a lack of funding since December 22 after Trump demanded $US5.7 billion ($A7.9 billion) from Congress to build a security wall on the southwest US border.
Democrats, who control the House of Representatives, have rejected Trump's demand, as have Senate Democrats who are needed to pass most legislation in the chamber even though Republicans have a majority.
On Sunday, Republican Senator Lindsey Graham urged Trump to reopen the government for a short period of time in an effort to restart talks. It is an idea that Democrats have been urging for weeks.
"Well, that was a suggestion that Lindsey made but I did reject it," Trump told reporters as he left the White House for a trip to Louisiana.
"I want to get it solved, I don't want to just delay it."
The partial shutdown is the longest in US history and has seen Trump lurch from one idea to another in an attempt to secure money for building a wall that he argues is needed to secure the US against illegal immigrants and drugs.
Democrats say there are cheaper, more effective ways of enhancing border security than constructing a wall that could cost well beyond $US 25 billion. They have offered $US1.3 billion for this year in new border security funds to pay for a range of high-tech and other tools at the border.
Last week Trump suggested that a renegotiated trade deal with Mexico could bring in the revenues needed to build the wall or that military funds and US soldiers could be utilised.
The administration said it was looking into the president declaring a "national emergency" and redirecting US Army Corps of Engineers funds to the wall.
But on Monday, Trump said: "This is so simple you shouldn't have to. Now I have the absolute legal right to call it but I'm not looking to do that."
Some leading Republicans have publicly opposed the idea, which almost certainly would trigger lawsuits over its legality.
The House last week passed four separate bills to fund and reopen several agencies, including the Departments of Agriculture and Treasury, the National Park Service and the Securities and Exchange Commission.
Trump opposes these bills and Senate Majority Leader Mitch McConnell, a Republican, has refused to bring any funding bill up for a vote without the president's support.
"It's time for you to stop standing in the way of re-opening the government. Let the Senate vote!" House Speaker Nancy Pelosi said in a Twitter post directed at Trump on Monday.
The stress from the shutdown became more visible as 800,000 federal employees across the US missed their first paychecks on Friday.
The cut government services also affected travellers as a jump in unscheduled absences among federal airport security screeners forced partial closures of airports in Houston and Miami.
National parks also remain shut, food and drug inspections have been curtailed and key economic data is on hold, among other impacts.
Federal courts are set to run out of money on Friday.