(CNN) President Donald Trump's pick to be the next director of national intelligence, which has oversight over the CIA, has pushed for the Justice Department to investigate what role the agency and the broader intelligence community played in starting the counterintelligence investigation into Trump's team and Russia.

The comments from Rep. John Ratcliffe in television appearances and closed-door interviews with Obama administration officials questioning the US intelligence community's actions during the Russia investigation show how the Texas Republican aligns with the President's skepticism of the entire Russia probe, which ultimately became special counsel Robert Mueller's investigation.

Ratcliffe was one of the key Republicans leading the GOP-run congressional investigation into the FBI and Justice Department's handling of the Hillary Clinton email and Trump-Russia investigations last year. Ratcliffe had a central role in interrogating FBI and Justice Department officials on how the investigation began, and it helped Ratcliffe get on the radar of the President, who often seized on developments in the congressional investigation and twice this year tweeted about Ratcliffe's Fox News interviews.

A CNN review of the Republican-led interview transcripts from their FBI investigation, as well as dozens of Ratcliffe's Fox News appearances of the past year, reveal his deep skepticism of not just the FBI and Justice Department actions in 2016, but also of the intelligence community he would lead if confirmed to succeed Dan Coats as director of national intelligence.

Ratcliffe's worldview that emerged from his role in investigating the Russia investigation will now be thoroughly examined as he heads into the confirmation process to lead the Office of the Director of National Intelligence, particularly from Democrats who are criticizing his selection as overtly political.

While Ratcliffe didn't call for Mueller's removal or use inflammatory language like Trump -- he never called it a "witch hunt" or "a hoax," for instance -- Ratcliffe questioned the actions of the former special counsel, argued that the beginning of the investigation had tainted his findings and accused Obama officials of potentially committing crimes. The Texas Republican criticized both President Barack Obama's CIA Director John Brennan and DNI John Clapper, his potential predecessor.

"Think about that, a dossier funded by the Democrats, peddled through the Obama intelligence community, falsely verified by the Obama Justice Department, then sold to the American people by those very same elected Democrats and willing folks in the media," Ratcliffe said in a March 24 interview with Fox News' Maria Bartiromo, the morning before Attorney General William Barr released his letter summarizing Mueller's findings

Trump signaled Tuesday that he expects Ratcliffe to clean house, telling reporters that he had picked Ratcliffe in order to "rein in" the intelligence agencies.

"I think we need somebody like that that's strong and can really rein it in," Trump said. "As you've all learned, the intelligence agencies have run amok. They've run amok."

Democrats say they will mount a fight against Ratcliffe's confirmation, and moderate Democrats like Sen. Joe Manchin of West Virginia are voicing their opposition to the three-term Republican. "Anyone in the intelligence (community) should not be political at all. You have to get to the most non-political, non-partisan person you can find," Manchin said Tuesday. "Why bring in someone who is so toxic?"

While many Senate Republicans have said they want more information before making a judgment on Ratcliffe, Senate Intelligence Chairman Richard Burr has signaled he will back Ratcliffe's nomination, praising his experience as a US attorney and serving on the Intelligence and Homeland Security committees.

Senate Judiciary Chairman Lindsey Graham, who says his committee will also investigate the origins of the Russia investigation, said the intelligence community's role was a legitimate area for the Justice Department to probe.

"I think they should look at the FISA warrant. I think there's a lot of potential abuse," Graham said. "I think Ratcliffe's got a worldview that I share, that he believes in a strong military, in engaging our enemies, in leading from the front not behind, so I'm OK with him."

Ratcliffe's defenders argue he will win over his skeptics.

"I'm going to be really surprised at how many of his Democrat House colleagues that actually know him ... I'll be surprised they toe this line that he's some subjective loyalist incapable of putting his country ahead of his politics because anyone he knows him knows it's a damn lie," said former House Oversight Chairman Trey Gowdy, a South Carolina Republican.

Questions about the CIA

In recent weeks, Ratcliffe has endorsed Barr's investigation into the origins of the FBI's Russia probe, one in which the President has granted Barr declassification power and has instructed the intelligence community to cooperate.

"As he said, there was spying. The Obama Justice Department and intelligence community did spy on the Trump campaign. The question now that needs to be answered is, was there a predicate for that?" Ratcliffe told Bartiromo in an April interview. "This is why the focus needs to shift now to those folks in the intelligence community and at the Justice Department that made representations that there was probable cause, that there was evidence of collusion, when, in fact, the special counsel has found that there was none."

Ratcliffe himself has raised questions about the role of former Trump campaign aide George Papadopoulos -- who was interviewed by the committees in October -- in launching the Russia investigation in July 2016, which began when Australian diplomat Alexander Downer reported his conversation with Papadopoulos about Russian dirt to the FBI.

But Ratcliffe and other Republicans have raised questions about Papadopoulos and what role the CIA may have played in Downer's interactions with him.

"There's been so much focus on the FBI and the Department of Justice. But a lot of the questions that relate to the origins of this go to the CIA," Ratcliffe told Fox News' Martha MacCallum in June. "It was Alexander Downer who was John Brennan's CIA counterpart at one point in time for Australia that supposedly had this random conversation with George Papadopoulos that served as the predicate."

Investigating the Russia investigation

Gowdy helped elevate Ratcliffe into his role on the GOP-led investigation that was chaired by Gowdy and then-Judiciary Chairman Bob Goodlatte. A handful of lawmakers were part of a task force Gowdy and Goodlatte created that took the lead on questioning witnesses, which included Ratcliffe and close Trump ally Rep. Mark Meadows of North Carolina.

In the role, Ratcliffe questioned multiple witnesses who appeared behind closed doors before the committee in 2018, including former FBI Director James Comey, Papadopoulos and Peter Strzok and Lisa Page , the FBI officials who exchanged anti-Trump text messages that have fueled accusations that Mueller's probe was inherently biased.

"We have learned in the course of this investigation of incredible manifest bias from people like Peter Strzok and Lisa Page," Ratcliffe said in one contentious exchange with Comey. "I'm trying to determine the level of bias, if any, that Director Comey had with respect to President-elect or President Trump and why he would have violated his employment agreement to share information, classified or unclassified, with individuals who were not authorized to receive it."

When Strzok appeared before the panels in June 2018, Ratcliffe pushed him on whether Mueller's team had asked if the texts reflected bias, a point that Republicans hammered home when he appeared publicly the following month.

"So did Special Counsel Mueller or anyone with the special counsel investigative team make any inquiry as to whether or not any bias or prejudice reflected in that text that I just referred to impacted any actions or decisions or the manner in which the evidence you gathered, that information was affected?" Ratcliffe asked.

"So, if you're asking whether or not any -- if any of my personal beliefs ever influenced any official action, the answer to that is never," Strzok responded.

"I'm not asking that question," Ratcliffe responded. "I'm asking you whether the special counsel or anyone with the special counsel's investigative team made inquiry to you, whether or not any bias or prejudice that would be reflected in the text 'F Trump' impacted any actions that you took, any decisions you made, any information or evidence that you gathered?"

Ratcliffe was pitched for attorney general

Ratcliffe's sharp questioning of Mueller last week may have put the Texas Republican over the edge to become Trump's choice for the director of national intelligence, but Ratcliffe was a known commodity at the White House well before the special counsel probe concluded.

Gowdy, who considers Ratcliffe a close friend and has stayed in touch after leaving Congress, helped get the Texas Republican on Trump's radar last year for a different administration job: attorney general.

Gowdy said in an interview that he tried to set up a meeting with Trump to pitch Ratcliffe for the role after Jeff Sessions was fired in November 2018, but the meeting was delayed and Barr had already been selected.

Trump still met with Gowdy, which was Gowdy's first direct interaction with the President, giving him the chance to talk up Ratcliffe as a great candidate, Gowdy said.

Gowdy wasn't the only one pitching Ratcliffe. He was also floated by Fox News' Gregg Jarrett and former Rep. Jason Chaffetz on Fox News' "Hannity" the day that Sessions was ousted.

"By the way, I agree with Gregg, I hope that President Trump appoints John Ratcliffe, I think he is best person to do that," Chaffetz said.

A Fox News regular

Ratcliffe's role on the GOP-led investigation into the FBI and Justice Department made him a Fox News regular over the past two years.

In his interviews, Ratcliffe accused the Obama administration FBI and Justice Department of abusing the Foreign Intelligence Surveillance Act when it obtained a warrant on former Trump adviser Carter Page . He supported the release of the classified memo from then-House Intelligence Chairman Devin Nunes and joined the Republican calls for a second special counsel.

Ratcliffe charged the anti-Trump texts sent by Strzok, who was removed from Mueller's team over the messages, had poisoned the evidence that the special counsel might collect.

"I like the policy of extending clearances to former intelligence and law enforcement officials for the purpose of being able to provide advice and counsel to their successors, successive administrations, including the President," Ratcliffe told Bartiromo in August 2018. "I agree with the privilege. I also agree with revoking the privilege when it's been abused. So, in John Brennan's case, I think it's appropriate."

Since the special counsel's report was released, Ratcliffe has criticized House Democrats for continuing to claim evidence of collusion when Mueller did not establish a criminal conspiracy. But Ratcliffe was prescient nearly a year ago over the current political battle playing out in Congress -- an environment he would leave should he be confirmed as director of national intelligence.

"At the end of the day, where we are headed here is no charges for collusion or obstruction with anyone associated with the Trump campaign," he told Bartiromo on October 14, 2018. "But a report from Bob Mueller outlining perhaps some questionable conduct, and we will be left arguing with our Democratic colleagues whether that rises to an impeachable offense, even if it's not criminal in nature."