President Donald Trump offered a fulsome defense of Russian President Vladimir Putin over the weekend, leaving Republican lawmakers frustrated and flummoxed yet again by the president's warm feelings toward the rival nation.

In a Fox News interview, Trump, who during the campaign repeatedly praised Putin, again said he respected the Russian leader and hoped to get along with Moscow, and he seemed to equate the United States with its adversary when pressed by host Bill O'Reilly, who said, "But he's a killer though. Putin's a killer."

"There are a lot of killers," Trump said, in an interview that aired Sunday before the Super Bowl. "We've got a lot of killers. What do you think? Our country's so innocent?"

Trump's comments came even as his United Nations envoy, Nikki Haley, on Thursday condemned Russia's "aggressive actions" in eastern Ukraine and as both the Senate and House intelligence committees launched investigations into alleged hacking by Russia of the U.S. election that the intelligence community believes was intended to benefit Trump.

The issue of Russia dogged Trump's presidential campaign - including after a news conference where he suggested that Russia hack Hillary Clinton's emails - and his latest comments left Capitol Hill Republicans scrambling to distance themselves from the president and his unusually friendly stance toward Putin, who has praised the president as a "smart" man.

In an interview with CNN's "State of the Union" on Sunday, Senate Majority Leader Mitch McConnell, R-Ky., called Putin "a former KGB agent" and "a thug," and he rejected any comparison between the two nations, citing Russia's annexation of Crimea, its incursions into Ukraine and its interference in the U.S. presidential election.

"I don't think there's any equivalency between the way that the Russians conduct themselves and the way the United States does," McConnell said.

The senator added that while he hoped not to "critique the president's every utterance," he found significant differences between the two nations. "I do think America is exceptional. America is different," McConnell said. "We don't operate in any way the way the Russians do. I think there's a clear distinction here that all Americans understand, and no, I would not have characterized it that way."

House Speaker Paul Ryan, R-Wis., was similarly wary. "Speaker Ryan has consistently and frequently spoken out on Russia and Putin and made his opinions well known, including the need for continued sanctions," spokeswoman AshLee Strong said Sunday.

She pointed to Ryan's comments at a CNN town hall broadcast last month, where he called Russia a "global menace" and said Putin "does not share our interests; he frustrates our interests."

"Let me put it this way, the Russians are up to no good, we all know that," Ryan said, responding to a question about Russia's election meddling. "We've got to make sure going forward that we do everything we can on cyber, on all of the other things to make sure that they can't do this again."

Congressional Republicans have broken with Trump over dozens of controversial statements he has made during his campaign, his transition and now his presidency. But few issues appear to have confounded lawmakers as much as his consistent defense of Putin. Trump's coziness is at odds with years of Republican foreign policy orthodoxy calling for a more aggressive stance toward Putin's regime.

Sen. Marco Rubio, R-Fla., weighed in on Twitter with two missives that he personally penned. "When has a Democratic political activists ever been poisoned by the GOP or vice versa? We are not the same as #Putin," he wrote. In a second tweet, he said the United States should lift sanctions on Russia only if it ends its violations in Ukraine.

And Rep. Liz Cheney, R-Wy., the daughter of former Vice President Richard Cheney, also took to Twitter to say that Trump's "statement suggesting moral equivalence between Putin's Russia and the United States of America is deeply troubling and wrong."

Appearing on four Sunday shows, Vice President Mike Pence rejected the notion that Trump had equated Russia to the United States.

"I simply don't accept that there was any moral equivalency in the president's comments," Pence said on CBS' "Face the Nation." "There was no moral equivalency. What you heard there was a determination to attempt to deal with the world as it is - to start afresh with Putin and to start afresh with Russia."

Pressed by John Dickerson, the show's host, on whether he believed the United States was morally superior to Russia, Pence repeatedly dodged the question, instead finally saying, "American ideals are superior to countries all across the world."

Pence, who would not commit to maintaining sanctions against Russia if it continues to violate a cease-fire agreement in Ukraine, nonetheless took a slightly harder line than the president on Russia.

Asked on ABC's "This Week" whether the White House planned to put Russia on notice, as it had Iran, over violating the cease-fire, Pence said, "We're watching, and very troubled by the increased hostilities over the past week in eastern Ukraine."

But he also broadly defended his boss, saying, "There's a new style of leadership, not just a new leader in the White House."

"President Trump is bringing a very candid - and direct type of leadership to the White House," Pence said. "And in conversations with leaders around the world, frankly, I think they all find it very refreshing."

Not everyone seemed to agree. Gov. John Kasich of Ohio, who ran against Trump during the 2016 Republican primaries, issued a sharp rebuke on Twitter. "America has been a beacon of light and freedom," he wrote. "There is no equivalence with the brutal regime of Vladimir Putin."

House Minority Leader Nancy Pelosi, D-Calif., even called for an investigation by the FBI into Trump's financial, personal and political connections to Russia.

"I want to know what the Russians have on Donald Trump," she said on NBC's "Meet the Press." "We want to see his tax returns so we can have truth in the relationship between Putin, whom he admires, and Donald Trump."