“The House of Representatives will not consider a concurrent resolution authorizing the President’s State of the Union address in the House Chamber until [the] government has opened,” Pelosi wrote in her own brief correspondence, CNBC reports.

In order for the president to deliver the SOTU in front of a joint session of Congress, the two legislative bodies must pass a resolution to schedule it. With Pelosi standing her ground, this can’t happen.

Pelosi’s first letter, sent last week, suggests postponing the SOTU due to “security concerns” caused by the lack of funding for the U.S. Secret Service and the Department of Homeland Security during the government shutdown.

Trump took this quite literally, arguing Wednesday that security was covered, and thus he would be honoring Pelosi’s original invite to deliver his address.

“Even prior to asking, I was contacted by the Department of Homeland Security and the United States Secret Service to explain that there would be absolutely no problem regarding security with respect to the event. They have since confirmed this publicly,” Trump wrote.

“Therefore, I will be honoring your invitation, and fulfilling my constitutional duty, to deliver important information to the people and Congress of the United States of America regarding the State of our Union,” he continued. “It would be so very sad for our country, if the State of the Union were not delivered on time, on schedule, and very importantly, on location!”

By negating Pelosi’s logistical reasoning and pointing out that she originally invited him on Jan. 3—already more than a week into the shutdown—Trump was daring Pelosi to admit her letter was retribution for maintaining the shutdown and officially uninvite him.

Pelosi responded to the challenge.

“When I extended an invitation on January 3rd for you to deliver the State of the Union address, it was on the mutually agreed upon date, January 29th. At that time, there was no thought that the government would still be shut down,” Pelosi wrote Wednesday.

“In my further correspondence of January 16th,” she continued, “I said we should work together to find a mutually agreeable date when [the] government has re-opened and I hope that we can still do that.”

The power play between the two has been ongoing since Trump first told Pelosi and Senate Minority Leader Chuck Schumer that he would be proud to shut down the government over border security last month.

As that threat of a shutdown became a reality, both Trump and the Democrats have dug in their heels. Trump wants $5.7 billion for a border wall, but Democratic leadership refuses to give it. Meanwhile, government workers continue to go on without paychecks, and Trump’s approval rating has hit an all-time low.

Trump denied Pelosi military transport for a trip abroad after she suggested he postpone the SOTU, citing “the 800,000 great American workers not receiving pay,” but First Lady Melania Trump reportedly used another military aircraft to fly to Florida just hours later for a weekend vacation.

Trump and Pelosi’s letters appear to be diplomatic snubs, veiling criticism for a lack of movement at the negotiation table that each blames on the other.

Pelosi just brought that fight to the forefront, and Trump said he’s “not surprised.”

Speaking from the White House after Pelosi’s letter went public, Trump said the Democrats have become “radicalized,” CNN reports. Trump added that the Democrats “don’t want to see crime stopped,” referring to his argument that a border wall would decrease criminal activity.

In terms of a new venue for the SOTU, Trump said: “We’ll see.”