Senate Judiciary Committee Chairman Chuck Grassley Charles (Chuck) Ernest GrassleyGOP lawmakers distance themselves from Trump comments on transfer of power The Hill's 12:30 Report: Ginsburg lies in repose Top GOP senators say Hunter Biden's work 'cast a shadow' over Obama Ukraine policy MORE (R-Iowa) wants the panel to investigate any attempts to influence FBI investigations under the Trump and Obama administrations.

"There should be no improper interference with FBI investigations to favor any elected official or candidate of either party. The Committee has an obligation to pursue all evidence of such misconduct," Grassley wrote in the letter, which was publicly released on Wednesday.

Comey has raised concerns about Attorney General Loretta Lynch's actions around the FBI's investigation into Clinton's private email server.

He told the Senate Intelligence Committee last week that he felt "queasy" after Lynch asked him to characterize his probe into Clinton's emails as a "matter," rather than an investigation.

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Feinstein told CNN over the weekend that Congress should investigate if Lynch asked Comey to cover for Clinton's presidential campaign, but any probe should be kept separate from the committee's ongoing investigations into Russian interference in last year's election.

But Grassley wrote in his letter that they disagree about if an investigation into Lynch should be separate from their other work, noting the administration initially pointed to the Clinton case to justify firing Comey.

"The Administration has referenced both Mr. Comey’s handling of the Clinton investigation and Russia investigation as factors in his decision to fire Mr. Comey," Grassley wrote.

The Trump administration initially used a memo from Deputy Attorney General Rod Rosenstein as the justification for firing Comey. Trump, however, has said he was prepared to fire the former FBI director regardless of the Justice Department's recommendation, and signaled the Russia probe was on his mind when he made the decision.

Grassley also pointed to Trump's statements that Comey told him he was not under investigation, saying it was "clear" the president "was not happy" about Comey's refusal to publicly say that the president wasn't under investigation.

"That reference, combined with Mr. Comey’s testimony last week that he refused the President’s asks to state that fact publicly, make it clear that the President was not happy with Mr. Comey’s actions on that issue, and frankly, that makes perfect sense," Grassley wrote.

Grassley's letter isn't the first time he's signaled that the committee should investigate the now-closed probe into Clinton's email setup.

The committee invited Comey to testify earlier this year on both Russia election interference and Clinton's private email server, but Comey declined the investigation.

Both the Judiciary Committee and Intelligence Committee in the Senate are investigating Russia's election interference and potential contacts between the Trump campaign and Moscow. Grassley has signaled he's willing to subpoena Comey to come before the Judiciary panel if he won't do so voluntarily.

He added in his letter that issues under the committee's jurisdiction include Comey's firing, election interference and "other high-profile, politically-charged investigations such as the handling of the Clinton email investigation."

"It is my view that fully investigating the facts, circumstances, and rationale for Mr. Comey’s removal will provide us the opportunity to do that on a cooperative, bipartisan basis," he said.