Rep. Adam SchiffAdam Bennett SchiffDebate builds over making Mueller report public Media reliability questioned over report Trump directed lies to Congress Giuliani defends Trump going after Cohen's father-in-law MORE (Calif.), the top Democrat on the House Intelligence Committee, offered high praise for Sen. John McCainJohn Sidney McCainGrassley to test GOP on lowering drug prices Listen, learn and lead: Congressional newcomers should leave the extremist tactics at home Overnight Defense: Trump unveils new missile defense plan | Dems express alarm | Shutdown hits Day 27 | Trump cancels Pelosi foreign trip | Senators offer bill to prevent NATO withdrawal MORE on Friday, saying the Arizona Republican's vocal criticism of President Trump marks his "finest hour."

"I think frankly this is John McCain's finest hour," Schiff said on HBO's "Real Time with Bill Maher."

"Probably his most important public service since Vietnam is what he is doing now. I wish we had more Republicans in the House, or maybe even one in the House, who is willing to follow his example."

McCain has been adamant in his calls for an independent commission to investigate Russia's efforts to meddle in the 2016 presidential election, as well as the Trump campaign's alleged ties to Moscow.

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The senior Arizona senator has also been critical of Trump's "America first" approach to foreign policy, saying earlier this month that "it's more confusion than anything else."

More recently, McCain has taken aim at the president over his decision to fire FBI Director James Comey, a decision he called disappointing. He told foreign officials on Tuesday at a meeting of the Munich Security Conference that if Trump hoped to interrupt the FBI's ongoing Russia investigation it would not work.

"I regret it, I think it’s unfortunate," McCain said. "The president does have that constitutional authority. But I can’t help but think that this is not a good thing for America."

The House Intelligence Committee is conducting its own probe into Trump and his aides' potential ties to Russia, and Schiff has been a vocal proponent of accelerating the investigation.