After a high-stakes back and forth between the top Democrat and Republican on the House Intelligence Committee, Sen. John McCain says partisan bickering has cost Congress its credibility to investigate alleged Russian interference in last year's election.

"I have not seen anything like it," McCain said Thursday on TODAY about the infighting. "It is very disturbing."

McCain, R-Ariz., said it's up to House leadership to decide whether to change how the investigation is being conducted, and on Wednesday called for a congressional select committee or independent commission to take charge. Republican leaders on Capitol Hill have so far resisted such a move.

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"No longer does the Congress have credibility to handle this alone, and I don't say that lightly," McCain, the chairman of the Senate Armed Services Committee, told MSNBC's Greta Van Susteren on Wednesday.



Earlier in the day, Devin Nunes, the Republican Chairman of the House Intelligence Committee, announced that he had new evidence showing communications of President Donald Trump's transition officials may have been incidentally collected by U.S. intelligence surveillance.

Trump said he felt somewhat vindicated by the news, after spending weeks on defense about his unsubstantiated claim that former President Barack Obama had wiretapped him.

McCain said Nunes' revelation of new evidence hasn't changed his mind about whether the Obama administration ordered any surveillance.

"I think the president can obviously express his views and emotions, but nothing has changed since the director of the FBI said there was no evidence that Trump Tower had been 'wiretapped,'" McCain told TODAY.

Democrats on the House Intelligence Committee on Wednesday were furious after learning that Nunes, a former Trump transition official himself, briefed Trump on the matter first before them.

"It's simply not possible to do a credible investigation if you take information that's pertinent to the scope of what you're investigating and bring it to the White House instead of bring it to your own committee," Rep. Adam Schiff, the top Democrat on the Intelligence Committee, told MSNBC's Chuck Todd, adding that there was "more than circumstantial" evidence of collusion between Trump associates and Russia.

Surveying the entire Nunes-Schiff exchange, McCain called it "bizarre" and criticized both lawmakers.

"This just shows a tremendous chasm between the two senior members of the House Intelligence Committee," the veteran senator told Van Susteren.

"There is no substantiation for what Chairman Nunes said, nor is there substantiation for what Congressman Schiff said," he added.

McCain said we know "for sure" that Russia interfered in the election, but also said, "They did not achieve in affecting the outcome."

Asked about Trump's claim of vindication, McCain responded, "I have long ago given up on trying to interpret the remarks of the president of the United States."