Speculation in Washington DC is that President Trump is preparing to fire Robert Mueller, the special counselor who is running the investigation to see if the Trump campaign colluded with the Russians leading up to the 2016 election.

In response to those rumors, Rep. Jackie Speier (D-Calif.) on Sunday warned that if President Trump orders the firing of special counsel Robert Mueller, she will vote to impeach him.

The tweet reads: “The President is careening us toward what I fear will be a constitutional crisis. Mr. President: Here is my red line—Fire Mueller and I will vote to fire you.”