Sean Hannity is the latest conservative political figure to use Twitter to attack Sen. Ben Sasse, whom he called “useless” and a “#loser” on Thursday.

The virtual fisticuffs began when the Fox News host responded to a statement Sasse released Thursday calling out President Donald Trump for challenging some network news outlets’ licenses.

“Mr. President: Words spoken by the President of the United States matter,” the Nebraska Republican wrote. “Are you recanting of the Oath you took on Jan. 20 to preserve, protect, and defend the First Amendment?”

Hannity, one of Trump’s strongest allies in the media, did not appear to feel the same way about the president.

“One of the biggest mistakes in my career was supporting @BenSasse,” he said, responding to Sasse’s statement.

One of the biggest mistakes in my career was supporting @BenSasse Just useless. https://t.co/bYReWFdfKO

— Sean Hannity (@seanhannity) October 12, 2017

Sasse did not let it stop there. He said Hannity was the one whose politics had changed since Hannity endorsed Sasse in 2014 and reiterated his point that presidents “should not play with censoring news they dislike.”

On Wednesday, Trump caused another set of ripples when he lit into NBC News for negative coverage of his administration and questioned its licensing. He later expanded that challenge to all network television.

“Network news has become so partisan, distorted and fake that licenses must be challenged and, if appropriate, revoked,” Trump tweeted Wednesday.

Later Thursday, Hannity launched a flurry of five tweets aimed at Sasse.

He advised Sasse to focus on repealing Obamacare (and to give him a call when he has done so), told the senator he has “accomplished NOTHING IN DC,” stood up for the president, whom he said “keeps his promises,” and staged a hardly coherent attack on the “Fake News Media.”

The @POTUS keeps his promises. You criticize the Potus daily. How about standing up to McConnell? Call me when u repeal Obamacare #Loser https://t.co/H2T262MOxc

— Sean Hannity (@seanhannity) October 13, 2017

Sasse is known to use Twitter as a verbal boxing ring with political adversaries.

In September he unleashed a volley on alt-right leader Richard Spencer, calling the white supremacist a “clown” and a “brown-shirt-pajama-boy Nazi” and implying he and other neo-Nazis lived in their parents’ basements.

He also uses the app in jest, weighing in on trivial matters like the embattled rock group Nickelback and flan, a popular Hispanic dessert.