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 Mr. Sessions' chief of staff, is expected to take over oversight of Mr. 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 Mr. Whitaker ending or suppressing the Russia probe is not an option as of now.

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

He argued that Mr. 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 Mr. 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, Mr. Whitaker also told CNN's Don Lemon that he could see a scenario where Mr. Sessions is replaced with an attorney general who "reduces [Mr. Mueller's] budget so low that his investigation grinds to almost a halt."

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

Mr. 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 Mr. Trump and led to the deterioration of their relationship.

Mr. 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.

First Published: November 7, 2018, 9:42 p.m.