Democratic California Rep. Ted Lieu said Thursday that a “cloud of treason” hangs over the Trump administration.

“Cloud of treason means we must have total shutdown of any [President Trump] agenda item. No votes on any item,” Lieu tweeted.

Treason is a crime that is punishable by death. Democrats have been sharpening their rhetoric against Trump as allegations build of collusion between his campaign and the Russian government. For instance, Democratic Rep. Maxine Waters has repeatedly called for impeachment.

The FBI is currently investigating whether collusion with the Kremlin occurred. House Intelligence Committee ranking member Adam Schiff has said there is more than circumstantial evidence regarding this matter. However, Republican members of the committee have said this evidence doesn’t exist.