Democrats have asked President Donald Trump to postpone a speech to Congress, arguing security cannot be guaranteed due to the government shutdown.
Speaker of the House Nancy Pelosi said in a letter to Mr Trump that he should deliver the speech in writing instead unless federal agencies reopen.
Mr Trump is due to address Congress for the annual State of the Union speech on 29 January.
The US government is partially shut due to a row over border security.
The Republican president is demanding $5.7bn (£4.4bn) of congressional funding to build a wall on the US-Mexico border, but newly empowered Democrats have refused.
What did Pelosi say?
In Wednesday’s letter, Mrs Pelosi cited the “extraordinary demands presented” by the State of the Union speech as a reason for postponing.
She wrote: “Both the US Secret Service and the Department of Homeland Security have not been funded for 26 days now – with critical departments hamstrung by furloughs.
“Sadly, given the current security concerns and unless government re-opens this week, I suggest we work together to determine another suitable date after government has re-opened for this address or for you to consider delivering your State of the Union address in writing to Congress on January 29th.”
After a party leadership meeting she suggested to reporters that Mr Trump could give his speech from the White House Oval Office “if he wants”.
The White House did not immediately respond to Mrs Pelosi’s request.
Has this speech ever been delivered in writing before?
The US constitution requires that the president “shall from time to time give to the Congress Information of the State of the Union”.
According to the US National Archives, both the first US President, George Washington, and his successor, John Adams, delivered their speeches in person.
It was the third US President, Thomas Jefferson, who began the practice of delivering his State of the Union addresses in writing.
This was the tradition for more than a century until President Woodrow Wilson spoke in person to a joint session of Congress in 1913.
With rare exceptions, all subsequent US presidents have opted to appear in person on Capitol Hill every year to deliver this message setting out their administration’s aims and achievements.
The event is attended by every member of the US Senate and House of Representatives, justices from the Supreme Court and military leaders.
More on the US government shutdown
How is the shutdown affecting the economy?
The partial shutdown, now on day 26, is inflicting more damage to the US economy than previously predicted, a White House advisor has said.
The White House Council of Economic Advisers on Tuesday doubled projections of how much economic growth is being lost each week the standoff continues.
Its chairman, Kevin Hassett, said that initial estimates of the impact did not fully factor in private companies that have federal government contracts.
Economists say that while the blow to the overall economy remains a glancing one so far, it could become a direct hit if the shutdown is not resolved by next month.
How is it affecting unpaid workers?
Some of the 800,000 federal employees who have been going unpaid since 22 December are in increasingly dire straits.
More than 1,500 appeals have been set up by them on crowdfunding site GoFundMe, according to a company spokeswoman.
Many of the fundraisers are requesting a financial lifeline for government employees to pay their rent or feed and clothe their children.
On Wednesday, the president is expected to sign legislation backdating wages for 800,000 federal employees, who are going currently unpaid, whenever the shutdown ends.
The Department of Agriculture, the Internal Revenue Service and the Federal Aviation Administration have recalled more than 50,000 employees to help process tax returns, ensure aviation safety and staff farm offices.
What does the American public think?
According to a Pew Research Center opinion poll, a divide in public support for the wall is continuing to widen.
The survey, released on Wednesday, finds that 58% of Americans oppose building any new walls on the US-Mexico border, while 40% support the measure.
Nearly 88% of those opposed say it would be wrong for Congress to pass a bill that includes any border wall funding, even if it is the only way to end the shutdown.
Among those that support the wall, 72% say any bill that ends the shutdown would be unacceptable without Mr Trump’s wall funding.