Sen. Marco Rubio (R-Fla.) on Sunday gently expressed his disagreement with President Donald Trump over his defense of Russian President Vladimir Putin.

During an interview with Fox News that is scheduled to air later Sunday prior to the Super Bowl, Trump dismissed host Bill O’Reilly’s characterization of Putin as “killer,” suggesting America was on equal footing as the authoritarian regime.

“We’ve got a lot of killers,” Trump said. “What do you think? Our country’s so innocent?”

Rubio pushed back with a tweet that was signed “MR,” signifying that it was personally written by the senator.

When has a Democratic political activists been poisoned by the GOP, or vice versa? We are not the same as #Putin. MR — Marco Rubio (@marcorubio) February 5, 2017

Critics of former KGB officer Putin over the years have been found dead, often from poisoning. Vladimir Kara-Murza, who is part of a group calling for open elections and civil rights reforms in Russia, suffered multiple organ failure just this week after his second suspected poisoning. He remains in a coma.

During an interview on ABC’s “This Week,” Sen. Ben Sasse (R-Neb.) said the U.S. was “not at all” like Russia.

“There is no moral equivalency between the United States of America, the greatest freedom-loving nation in the history of the world, and the murderous thugs that are in Putin’s defense of his cronyism,” he said Sunday.

Over the course of the campaign and his nascent presidency, Trump has attacked a long litany of people, organizations and allies in the West. Putin and Russia have never made the list. Most recently, a statement the State Department released in response to increased hostilities in Ukraine this week made no mention of Russia’s role in the fighting.

Asked about the matter on on NBC’s “Meet the Press,” Vice President Mike Pence said he did not view Trump’s comments about Putin and the U.S. both killing people as a moral equivalency.

“What you have in President Trump is someone who is not going to look in the rear-view mirror,” he said.