Washington CNN  — 

The man taking over the Justice Department following Jeff Sessions’ firing as attorney general has argued that special counsel Robert Mueller’s investigation went too far.

Matthew Whitaker, who was Sessions’ chief of staff, is expected to take over oversight of Mueller’s investigation into Russian interference in the 2016 election and whether Trump campaign associates colluded with Russia. A source close to the President told CNN that the idea of Whitaker ending or suppressing the Russia probe is not an option as of now.

Trump’s dismissal of Sessions has raised yet more questions over how much influence the President will have over Mueller’s probe, which has been a source of pain since it began in spring 2017. Trump has complained repeatedly about Mueller’s investigation, calling it a “witch hunt,” and slammed Sessions in public repeatedly for recusing himself from the Russia probe, a step that helped lead to Deputy Attorney General Rod Rosenstein appointing Mueller.

In a CNN op-ed written last year, Whitaker argued that Mueller is “dangerously close to crossing” a red line following reports that Mueller was looking into Trump’s finances.

He argued that Mueller does not have “broad, far-reaching powers in this investigation,” but that the investigation’s limits are clearly defined by Deputy Attorney General Rod Rosenstein’s May 2017 letter appointing Mueller.

“It is time for Rosenstein, who is the acting attorney general for the purposes of this investigation, to order Mueller to limit the scope of his investigation to the four corners of the order appointing him special counsel,” he wrote then. “If he doesn’t, then Mueller’s investigation will eventually start to look like a political fishing expedition.”

Back in 2017, Whitaker also told CNN’s Don Lemon that he could see a scenario where Sessions is replaced with an attorney general who “reduces (Mueller’s) budget so low that his investigation grinds to almost a halt.”

Trump announced on Twitter Wednesday that Whitaker would fill the role of attorney general while he finds a permanent replacement to be “nominated at a later date.”

Sessions recused himself from the Russia investigation after it emerged that he had failed at his Senate confirmation hearing to disclose two pre-election meetings with Russia’s ambassador to Washington at a time when Moscow was accused of interfering in the presidential race. The recusal was harshly criticized by Trump and led to the deterioration of their relationship.

Whitaker was a CNN legal commentator and former US attorney who directed the Foundation for Accountability and Civic Trust (FACT), a conservative ethics watchdog group. He ran in the Republican primary for Iowa Senate in 2014.

Whitaker had taken a firm stance against Hillary Clinton while at the group.

He argued in 2016 that “there was a strong case” to bring against Clinton in the FBI’s investigation.

On the day that then-FBI Director James Comey said he wouldn’t recommend criminal charges against Clinton into her use of a private email server while she was secretary of state, Whitaker penned an op-ed in USA Today arguing that she should be prosecuted.

“Our judgment is that no reasonable prosecutor would bring such a case,” Comey said at a news conference in July 2016.

“I disagree,” Whitaker wrote hours after. “I believe myself to have been a reasonable prosecutor, and when the facts and evidence show a criminal violation has been committed, the individuals involved should not dictate whether the case is prosecuted.”

Whitaker has a personal tie to one of the witnesses in the Mueller investigation: Whitaker was the campaign chairman for Sam Clovis in 2014 when Clovis ran for state treasurer in Iowa, according to an archived press release on Clovis’ website.

Clovis, who worked on the Trump campaign, said in a May radio interview that he has been interviewed by Mueller’s team and had testified before the grand jury. Clovis was also listed an unnamed “campaign supervisor” in the indictment of former Trump campaign aide George Papadopoulos, according to The Washington Post.

Here are other comments Whitaker made on CNN regarding the Mueller investigation:

  • “CNN Tonight” in July 2017: “Really, I think ultimately what the President’s going to start doing is putting pressure on Rod Rosenstein, who is in charge of this investigation as acting attorney general, and really try to get Rod to cut … the budget of Bob Mueller and do something a little more stagecraft-y than the blunt instrument of firing the attorney general and trying to replace him.”
  • “CNN Tonight” in July 2017: “First of all, Bob Mueller was the FBI director when I was US attorney. I have a lot of respect, and I would be surprised if he is ultimately worried at all about this, and in fact I don’t even think he pays attention to what’s going on in the daily back and forth whether Jeff Sessions has the confidence of the President. Bob Mueller’s going to continue to do his investigation.”
  • “CNN Tonight” in August 2017: “If Bob Mueller and his small US attorney’s office, as I’ve heard it described today, does go beyond the 2016 election and get into Trump Organization finances unrelated to the 2016 election, and really unrelated to Russian coordination if it even exists, I think that would be crossing a red line and I think that’s when the deputy attorney general, who is the acting attorney general for the purposes of this investigation, Rod Rosenstein, who I served with in the Bush administration – he needs to step in and pull the reins back on Bob Mueller if he starts to go outside of those bounds of his delegation of authority.”
  • “At This Hour” in August 2017: “It would be a fishing expedition if they start looking into essentially all of Trump’s finances, and I know that’s what some on the left want, but there is a Fourth Amendment issue even as it relates to the President and others in his family that we just cannot have unfettered prosecutors turning over every rock that are unrelated to any like nexus to the underlying issues, which is the Russian coordination in the 2016 election.”

CNN’s Laura Jarrett, Jeremy Herb and Pamela Brown contributed to this report.