House Speaker Nancy Pelosi (D-CA) on Wednesday called for President Trump to postpone his upcoming State of the Union address, citing the likelihood that the government would be shut down during the day he’s slated to give it.

“Sadly,” Pelosi wrote in a letter to Trump, “given the security concerns and unless government re-opens this week, I suggest that 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 the Congress on January 29th.”

The letter, which comes as the White House is attempting to persuade moderate House Democrats to break ranks and vote for border-wall funding, demonstrably raises the political stakes of a shutdown fight that now is the longest in American history.

While there is no formal obligation that the president deliver an actual address before Congress on a yearly basis—merely that he or she update lawmakers on the state of the union—a high-profile speech has become a ceremonial rite of passage for a president. Pelosi’s insistence that one not take place while the government is closed is both a clear assertion of power on her part and a strategic attempt to deprive Trump of the stage he craves.

“She understands the symbolism of [the speech] happening when the government is shut down is inappropriate,” one Democratic lawmaker said. “It’s kind of bizarre that you shut the government down and then would come and give a speech on the state of the union. The state of the union is closed,” another Democratic lawmaker said. “Also, knowing how desperately he wants to give this speech, this is just going to drive him crazy!”

The White House did not immediately return a request for comment on Pelosi’s letter. But her letter sparked both anger among Republicans and a bit of begrudging respect for its boldness.

“It shows she has leverage and is willing to use it [and] it hits Trump where it hurts—massive media attention,” said Doug Heye, who, as Republican National Committee press secretary in 2010, led the Fire-Pelosi campaign that dislodged her as speaker that election cycle. “And I think this is being somewhat mis-reported. While the letter contains all the niceties and courtesies, Pelosi isn’t asking Trump not to come. She is telling him he won’t be allowed.”

Before sending her letter to Trump on Wednesday, Pelosi read it to her fellow Democrats during a caucus meeting in the morning. According to a lawmaker in the room, “there was a very positive reaction”—reflecting the unified front that the party has adopted during the shutdown fight.

In her letter, Pelosi noted that the government agencies responsible for managing security during the State of the Union, including the Secret Service and the Department of Homeland Security, “have not been funded for 26 days now–with critical departments hamstrung by furloughs.”

—Victoria Albert contributed reporting.