Republican Sen. John Cornyn pushed back Wednesday against efforts by House Democrats to obtain President Trump's taxes and financial records and seek testimony from former White House counsel Don McGahn.
"That's really not a legitimate scope of oversight... this is all for show," the Senate Judiciary Committee member said, adding that members of Congress know that "confidential communications" between a White House counsel and a president "have always been protected."
"Congress' role is to do oversight of the laws that we pass to see if new changes need to be made or reforms need to be considered," he explained.
McGahn was directed by the White House not to appear before the House Judiciary Committee Tuesday.
Democrats want to hear from McGahn after he featured prominently in the Mueller report's obstruction of justice inquiry. Mueller's team concluded that McGahn was instructed by Trump to facilitate Mueller's removal in June 2017, but he did not comply with the request.
President Trump lashed out at Democrats on Twitter Wednesday, claiming they are trying to "prove the Mueller report wrong."
Later on Wednesday, Trump demanded Democrats end what he called their "phony investigations" before he'll negotiate with them on issues like infrastructure, as he delivered a fiery statement from the Rose Garden after cutting a meeting short with House Speaker Nancy Pelosi and Senate Democratic Leader Chuck Schumer.
The president had met for mere minutes with the two Democratic leaders in a session scheduled to discuss a possible bipartisan infrastructure package. But moments before that sit-down, Pelosi accused Trump of having "engaged in a cover-up" regarding the Russia probe.
Cornyn said Democrats "don't really know what to do" after the Mueller report's release, so they are continuing with a "partisan political drumbeat" toward impeachment.
He added that Pelosi is "caught in a box" because she knows pursuing impeachment could cause a "backlash" against her party in 2020.
Fox News' Alex Pappas contributed to this report.