California Democratic Rep. Maxine Waters told MSNBC's "Morning Joe" Thursday that there is no proof of collusion between President Donald Trump and Russia.

During a speech Tuesday at the Ideas Conference in Washington, D.C., Waters, who has been encouraging Democrats to talk more boldly about impeaching Trump, mocked fellow Democrats who were too afraid to speak out on the idea of impeachment, Rolling Stone reported.

Huffington Post editor Sam Stein, a frequent "Morning Joe" guest, asked Waters on Thursday what she meant when she accused Trump of "collusion" with Russia. Stein said that "collusion," to him, means something very specific and that most of the evidence cited by Waters so far seems circumstantial.

“I am talking about strategies that were developed, working with the Trump campaign. I really do believe that much of what you saw coming out of Trump’s mouth was a play from [Russia President Vladimir] Putin’s playbook,” Waters responded.

Waters explained that Trump calling Hillary [Clinton] "crooked" and encouraging talk about locking her up were strategies developed by Putin and the Russians. The congresswoman added that the Russians needed Trump in order to lift drilling sanctions in the arctic, turning a blind eye to the invasion of Crimea, and allowing the reunification of the Soviet Union.

“But just to be clear, there has been no actual evidence yet?” Stein asked.

“No, it has not been,” Waters admitted. “No, it has not. And I want you to know every time I’ve talked about impeachment I’ve said we’ve got to connect the dots, we’ve got to get the facts, we’ve got to do the investigation. That is what leads to impeachment, and I’ve also said that Trump will lead us right there.”

Other than Waters, only a few other Democrats have openly talked about impeaching Trump, including Rep. Al Green (D-Texas) and Rep. Joaquin Castro (D-Texas). Most Democrats are being cautious about the subject, following the lead of Rep. Adam B. Schiff (Calif.), the top Democrat on the House Intelligence Committee, who told the Times that “no one ought to, in my view, rush to embrace the most extraordinary remedy that involves the removal of the president from office.”

Democrats are reportedly planning to poll test the idea of impeaching Trump, fearing political fallout from voters should urging impeachment prove unpopular. Democratic strategists predict that the party's focus will be more on urging independent investigations than calls for impeachment.