Sen. Lindsey Graham Thursday called for Russians to "step up" and kill President Vladimir Putin amid Russia's brutal war on Ukraine – then doubled down on the comments Friday morning. 

"Somebody in Russia has to step up to the plate. Is there a Brutus in Russia? Is there a more successful Colonel Stauffenberg in the Russian military," Graham, R-S.C., said on "Hannity." 

Brutus was a Roman politician who killed dictator Julius Caesar and Stauffenberg was a German military officer who attempted to assassinate Adolf Hitler. 

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"This only way this ends my friend is for somebody in Russia to take this guy out," Graham continued. "You would be doing your country a great service and the world a great service." 

Sen. Lindsey Graham, R-S.C., on Capitol Hill on Feb. 7, 2019. (AP Photo/J. Scott Applewhite, File)

Sen. Lindsey Graham, R-S.C., on Capitol Hill on Feb. 7, 2019. (AP Photo/J. Scott Applewhite, File)

Graham also repeated the "Hannity" comments in tweets. He said, "The only people who can fix this are the Russian people" and urged them to "step up to the plate" or else live the rest of their lives "isolated from the rest of the world." 

The senator's comments caused swift backlash by others, concerned they could provoke Putin and contribute to the U.S. getting dragged into a war between two of the world's preeminent nuclear powers. 

That pushback came from both sides of the aisle. 

"Seriously, wtf?" House "Squad" member Rep. Ilhan Omar, D-Minn., tweeted. 

"I really wish our members of Congress would cool it and regulate their remarks as the administration works to avoid WWlll," she added. "As the world pays attention to how the US and its leaders are responding, Lindsey’s remarks and remarks made by some House members aren’t helpful."

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"While we are all praying for peace & for the people of Ukraine, this is irresponsible, dangerous & unhinged," Rep. Marjorie Taylor Greene, R-Ga., tweeted. "We need leaders with calm minds & steady wisdom. Not blood thirsty warmongering politicians trying to tweet tough by demanding assassinations."

And Russia's ambassador to the U.S. Anatoly Antonov called the comments "criminal," and "outrageous and unacceptable." 

Even after that pushback from his own party, Graham stood by the comments on "Fox & Friends" Friday morning, calling for Russians to "rise up and take [Putin] down." He responded by accusing Antonov of "supporting a war criminal in Putin."

"You, my friend, are the one who needs to apologize," Graham said.

Graham also told "Fox & Friends" that he wants to see Putin, top Russian military officials and even the individual soldiers carrying out their orders, tried for war crimes Russia commits in Ukraine. 

Momentum is building in Congress behind an effort to ban Russian oil imports to the United States. Graham is one of the key sponsors of a bill introduced Thursday by Sens. Lisa Murkowski, R-Alaska, and Joe Manchin, D-W.Va. 

Sen. Ed Markey, D-Mass., and Rep. Andy Barr R-Ky., also each introduced their own versions of that legislation in recent days. 

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House Speaker Nancy Pelosi, D-Calif., said she supports the effort. And progressive Rep. Ro Khanna, D-Calif., told Fox News Thursday that banning Russian oil imports is an option President Biden should take seriously. 

"Nancy Pelosi is with us," Graham said at a press conference promoting the Manchin-Murkowski bill Thursday. "Which made me wonder, 'What I am doing?' She's right!"

"Putin brings everybody together," Manchin quipped in response to that comment from Graham. 

But Graham stands largely alone on his push for Russians to assassinate Putin. 

Sen. Ted Cruz, R-Texas, called Graham's comments an "exceptionally bad idea" Thursday night.