By Alexander Bolton and Katie Bo Williams - 08-07-17 06:00 AM EDT
Sen. Charles Grassley (R-Iowa) has emerged as a pivotal player in the controversy surrounding President Trump and Russia.
As chairman of the Senate Judiciary Committee, Grassley has threatened to subpoena Trump family members and associates over their roles in the controversy surrounding Russia's involvement in last year's election.
He has also defended Attorney General Jeff Sessions, whom he had privately urged to recuse himself from the Justice Department's investigation of Russian meddling given the former Alabama senator's support for Trump's campaign.
Grassley warned the White House that there will be no confirmation hearings this year on a new attorney general if Sessions is dismissed.
In June, Grassley criticized Trump's Office of Legal Counsel for an opinion holding that only committee chairmen have the constitutional authority to make official inquiries of the executive branch, not rank-and-file members.
Grassley shot that down emphatically.
"This is nonsense," he wrote in a letter to Trump.
The actions highlight Grassley's reputation as a dogged investigator - and an independent streak that has led him to embrace government whistle blowers.
"He's got a strong sense of right and wrong and I think that sense even surpasses party, which around here is a real virtue," said Sen. Dianne Feinstein (Calif.), the top-ranking Democrat on the Judiciary Committee.
Grassley and Feinstein displayed notable cooperation in their efforts to secure testimony from Paul Manafort, Trump's former campaign chairman, and Donald Trump Jr., the president's eldest son.
Committee staff are negotiating to sit down with both men. The committee is expected to seek information from Jared Kusher, Trump's son-in-law and a senior White House advisor, as well.
"This is vintage Chuck Grassley. He believes in strong oversight and he's going to be as aggressive as he feels like he needs to be in order to get it done," said Senate Republican Whip John Cornyn (R-Texas).
"Chuck Grassley has a reputation for rigorous oversight unmatched perhaps by anybody else in the Senate."
Grassley's committee is also trying to obtain memos that former FBI Director James Comey wrote of his interactions with Trump before his firing. His staff has reviewed the memos but doesn't possess them.
Grassley said in an interview that no one at the White House or within the Senate GOP leadership has tried to dissuade him.
"I've had no face-to-face contact with anybody, I've had no phone calls from anybody. Not only my colleagues but not from the White House either," he told The Hill.
Grassley has made investigations and oversight a priority throughout his career. As the Judiciary Committee chairman, he funnels a chunk of his resources into a seven-member team that is tasked almost exclusively with investigations - a rare set-up on Capitol Hill.
He operated a similar investigative unit with committee resources when he chaired the Senate Finance Committee.
One of his most high-profile investigations was of the gun-walking operation conducted by the Obama Justice Department, code named "Fast and Furious," that was linked to a firearm used in the death of Border Patrol Agent Brian Terry in 2010.
It became a major political headache for the Obama administration and led to former Attorney General Eric Holder being held in contempt by the House Oversight and Government Reform Committee for failing to share documents.
Grassley can be a partisan player.
Democrats excoriated him last year for refusing to hold confirmation hearings for Obama's Supreme Court nominee Merrick Garland. It was a rare instance when Democrats accused the senior Iowa senator of extreme partisanship.
He has sided with Trump at times in criticizing the FBI. Specifically he has pressed the FBI on its surveillance activities during the 2016 campaign, appearing to pursue the president's allegation that he was wiretapped.
With Sen. Lindsey Graham (R-S.C.) but without his committee's ranking member, Feinstein, he has asked the government to turn over any surveillance applications made by the FBI or the Justice Department in the course of the Russia investigation.
He also hammered former acting FBI Director Andrew McCabe - now the deputy director - for what he saw as conflicts of interest stemming from his wife's acceptance of political donations from Virginia Gov. Terry McAuliffe, who is a longtime Clinton ally.
Some Republicans worry that Grassley's investigation of Comey's firing could give Democrats a platform to criticize the president.
Senate Majority Leader Mitch McConnell (R-Ky.) made clear at the end of 2016, as allegations were ramping up that Russia interfered in the presidential election, that he wanted the Senate Intelligence Committee, which is headed by his close ally Sen. Richard Burr (R-Ky.), to take the lead.
When Grassley announced his committee would take a major role as well, it left some GOP colleagues grumbling that he had been pushed into it by Feinstein or more junior GOP members of his committee.
Sen. Orrin Hatch (Utah), a former chairman of the panel, said he did not know of any Republicans who saw a need to investigate Comey's firing.
"They want a political piece of the action," said another GOP colleague who requested anonymity to comment on the motives of Judiciary Committee members.
Grassley met with Burr about six weeks ago to coordinate their efforts. Mueller's office also gave the Judiciary panel the go-ahead to grill Manafort and Trump Jr. in a public hearing.
Stephen Kohn, a lifelong Democrat and founding partner of the nonpartisan firm Kohn, Kohn and Colapinto, which represents federal whistleblowers, and has worked with Grassley for 25 years said he represents the gold standard of impartial oversight on Capitol Hill.
"I've been around a long time and I can tell you other senator's and congressmen's oversight staffs are more political," he said. "If it's an issue against the president they support, it's not a good place to go. They just don't care."
Grassley will listen to and act on the allegations of a whistleblower whether there's a Republican or Democratic president in office, Kohn added.
In 1984, as a junior Republican, Grassley cited Reagan Attorney General William French Smith for contempt of Congress after the Justice Department failed to turn over records about whether General Dynamics, a military contractor, submitted fraudulent cost claims to the Navy.
In an effort to block Grassley, the then chairman of the Judiciary Committee, Sen. Strom Thurmond (R-S.C.), refused to schedule a meeting of his subcommittee.
Grassley went around his chairman by obtaining the contempt citation through the Joint Economic Subcommittee on international trade, finance and security economics.