Twitter users want President Donald Trump to unblock them--or face legal action.

"This Twitter account operates as a 'designated public forum' for First Amendment purposes,A Thought of Ecstasy and accordingly the viewpoint-based blocking of our clients is unconstitutional," reads a letter representing several Twitter users, including Holly O'Reilly, who was blocked after tweeting Trump a GIF of the president meeting Pope Francis.

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The attorneys argue that blocking users suppresses speech, since those blocked can't interact with Trump on Twitter anymore.

The letter, from the Knight First Amendment Institute at Columbia University, was also sent to Press Secretary Sean Spicer, the White House counsel and Dan Scavino, who heads social media for Trump.

While no lawsuit has been filed, the lawyers say they're considering one if Trump doesn't unblock their clients.

Another client, Joseph Papp, was blocked over the weekend when he tweeted about Pittsburgh after Trump mentioned the city in his speech about the Paris Climate Agreement. He included the hashtag #fakeleader and then was blocked.

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"Each of them was blocked soon after having disagreed with or ridiculed you," the letter reads.

The letter ends with the lawyers asking for the accounts to be unblocked in the name of protecting the First Amendment. Like they wrote in the letter, Twitter might not be a physical place, but since it's where Trump engages with people as a representative of the government, he can't just pick and choose who can use the platform. They argue the government "may not exclude people simply because it disagrees with them."

Makes you reconsider that @ tweet you were composing.