President Donald Trump could be trying to consolidate power in his presidency, according to Rep. Jackie Speier, D-Calif.

"I am concerned that the president of the United States is systematically trying to shut down every possible branch of government but the presidency," Speier said Tuesday on MSNBC.

"So you've got him attacking the judiciary, you have him attacking the CIA, you have him attacking the Department of Justice, the FBI. I mean, this is the conduct of someone who could become a tyrant if we don't step in and speak out against him," Speier said.

Trump's behavior is "so un-presidential," she said.

"He is undermining the very foundation of this country and the institutions that we hold so dear and that are protected in the Constitution of the United States."

Saturday and Sunday, Trump tweeted criticisms of Andrew McCabe, the FBI's deputy director.

Speier has criticized Trump before. On Dec. 12, she said there was a "rumor" that Trump would fire special counsel Robert Mueller before Christmas.