Although this year’s State of the Union is still two weeks away, Pelosi acted preemptively and effectively revoked an invitation she extended to Trump on the day she was sworn in as speaker. Noting that a State of the Union speech has never taken place during a government shutdown, she cited the possible impact of the funding lapse on security preparations by the Department of Homeland Security and the Secret Service. The State of the Union is annually designated as a “national special security event,” and as such, Pelosi wrote, requires “weeks of detailed planning with dozens of agencies working together to prepare for the safety of all participants.”

The Trump administration disputed Pelosi’s characterization of the shutdown’s impact on the State of the Union address. But the president alone doesn’t get to decide whether he’ll appear before Congress. The Constitution states that the president shall “from time to time give to the Congress information on the State of the Union.” The nation’s founding document says nothing, however, about a formal speech, or even that the presidential message be delivered every year.

Indeed, as Pelosi noted in her letter, presidents throughout the 19th century issued their State of the Union message in writing. In 1913, President Woodrow Wilson revived the practice started by George Washington, and continued by John Adams, of delivering a formal speech to Congress.

Presidents speak to Congress only by invitation and a joint resolution passed by the House and Senate. This is usually a formality, but if the 26-day shutdown continues, it won’t be this year. Weeks after Pelosi extended an invitation to Trump, Congress has yet to pass the resolution confirming the offer.

Neither the White House nor the Republican leadership in Congress responded to Pelosi’s letter in the initial hours after her office released it on Wednesday morning. But a spokesman for Senate Majority Leader Mitch McConnell noted on Twitter that although Pelosi cited the shuttered government as a reason for wanting to reschedule the speech, the shutdown had already begun by the time she invited Trump. Later in the afternoon, Homeland Security Secretary Kirstjen Nielsen contradicted Pelosi’s stated reason for wanting to reschedule the presidential address. “The Department of Homeland Security and the US Secret Service are fully prepared to support and secure the State of the Union,” she tweeted. “We thank the Service for their mission focus and dedication and for all they do each day to secure our homeland.”

Although a president has never delivered a State of the Union address while major parts of the government have been closed, the speeches have taken place in the midst of tense battles with Congress. In 1998, President Bill Clinton appeared before a Republican-led Congress in the Capitol just over a week after the revelation of his affair with Monica Lewinsky, which would lead to his impeachment by the House later that year. His State of the Union address the next year occurred while he was on trial in the Senate.