Sen. Dianne Feinstein (D-Calif.) speaks to President Trump during a meeting on immigration policy at the White House on Tuesday. (Jabin Botsford/The Washington Post)

President Trump labeled Sen. Dianne Feinstein as "Sneaky" in a Twitter attack Wednesday morning and urged Republicans to "take control" of the sprawling investigation into his administration and campaign and potential collusion with Russia.

Trump attacked Feinstein (D-Calif.) for releasing a transcript of private testimony from Fusion GPS co-founder Glenn Simpson on Tuesday — testimony from last summer that Republicans on the Senate Judiciary Committee had declined to release.

Simpson's political intelligence firm commissioned a dossier into Trump's Russia ties, and Republicans have used Simpson as a cudgel against the probe into the White House, saying that the dossier helped spur the investigation and should be discredited. Sens. Charles E. Grassley (R-Iowa), the committee chair, and Lindsey O. Graham (R-S.C.), also on the committee with Feinstein, made a criminal referral to the Justice Department, suggesting it investigate Christopher Steele, the British ex-spy who produced the dossier for Fusion, for possibly lying to the FBI.

Trump has attacked the dossier and called it "very fake," although its contents have not been proved or disproved. 

 "The fact that Sneaky Dianne Feinstein, who has on numerous occasions stated that collusion between Trump/Russia has not been found, would release testimony in such an underhanded and possibly illegal way, totally without authorization, is a disgrace. Must have tough Primary!" Trump tweeted. 

Last fall, Feinstein, 84, announced her decision to seek a sixth Senate term this year.

Trump also had an exchange with Feinstein over immigration during a meeting with congressional leaders at the White House on Tuesday.

During the part of the meeting open to news cameras, Trump appeared to agree with the California Democrat on making a deal on the Deferred Action for Childhood Arrivals, or "dreamers," program without other requirements that he and congressional Republicans have sought, including money to build a wall on the Mexican border. House Majority Leader Kevin McCarthy (R-Calif.) soon interrupted the president to try to steer him back on course.

The White House left the exchange out of an official transcript Tuesday but corrected it Wednesday morning after being asked about it.

Minutes after he slammed Feinstein on Twitter on Wednesday, Trump turned to the Russia investigation, which he called the "single greatest Witch Hunt in American history," added that "Russia & the world is laughing at the stupidity they are witnessing."

 The investigation led by special counsel Robert S. Mueller III has led to a guilty plea from former Trump national security adviser Michael Flynn and charges against former Trump campaign chairman Paul Manafort. A number of Trump's closest aides and associates have been interviewed, including his son-in-law and senior adviser Jared Kushner. The investigation is expected to last through much of the year. 

 It was unclear what Trump meant by saying that Republicans should take control. He has raged about the various congressional investigations into his administration, which are led by Republicans.

Feinstein told reporters Wednesday afternoon that by releasing the transcript, "people can make up their own minds" about what was said during the interview.

But she told reporters she intended to apologize to Grassley for not formally warning him of her plans.

"I want to apologize, because I wanted to talk to him first and I just got pressured and I didn't do it," she told reporters. "I owe him an apology, and I will give him an apology as soon as I see him. I think very often there are things that happen that no one ever sees can be used for all kinds of mysterious and bad purposes. That's really all I have to say."

When asked to clarify who might have pressured her to release the transcript, she took back her comment, saying, "I was not pressured."

It was not immediately clear whether Feinstein had apologized directly to Grassley as of Wednesday afternoon.

Reporters noted that Trump had suggested she released the transcript for political reasons to ward off a tough Democratic primary challenge by California state Sen. Kevin de León, who last year launched an upstart bid to unseat Feinstein.

"I'm not worried about it," said Feinstein, who has been in the Senate since 1992. "I've had tough primaries."

When pressed to respond to Trump's claim that her decision was politically motivated, Feinstein said: "Oh, come on. Do you believe that? Of course not. Of course not."