Sen. Chuck Grassley (R-IA) fired back Monday against President Donald Trump following the pair's ongoing feud over a Senate tradition known as the "blue slip,” with the senior Republican senator refusing to fold to Trump’s demands.

In July, Trump demanded that Grassley, who serves as Senate president, end the Senate tradition of blue slips, which are a tool that allows individual senators to block judicial nominees that would preside over their own districts, if confirmed. The president called Grassley a “RINO,” or "Republican in name only," and suggested that he "must hate America” for refusing to end the practice.

Grassley said he was “offended” by the initial attacks, and on Sunday, Trump doubled down in his effort to pressure Grassley into eradicating the blue slip. On Monday, Grassley finally fired back at the president’s demands in defending the practice of using blue slips.

“A U.S. attorney (or) district judge nominee without a blue slip does not have the votes to get confirmed on the Senate floor, and they don’t have the votes to get out of committee,” Grassley wrote in a social media post on X. “As chairman, I set up President Trump’s nominees for success, not failure.”

Now in a month-long recess, the Senate left dozens of Trump’s nominees unconfirmed when it adjourned earlier this month as Democratic lawmakers worked to stall their confirmation, sparking Trump to tell Senate Minority Leader Chuck Schumer to “go to hell!”

Now, as Trump works to pressure Grassley to amend Senate procedures by axing the blue slip, a number of GOP lawmakers, including among Trump’s most loyal supporters, have come to Grassley’s defense, and called on Trump to “back off” his demand.

“With respect, Mr. President, pretty please, with sugar on top, back off this, because I don’t think the Senate’s going to go along, and I think it’s just a needless fight,” said Sen. John Kennedy (R-LA) last month, following Trump’s initial attacks on Grassley.

In a subsequent social media post on Monday, Grassley further defended the use of the blue slip, pointing out that the Senate had managed to keep “30 liberals off (the) bench” during the Biden administration thanks to the procedure.

“The 100-year-old ‘blue slip’ (allowed) home state senators to have input on U.S. attorneys and district court judges in (the) Biden administration,” Grassley wrote in a social media post riddled with grammatical errors. “Republicans kept 30 liberals off (the) bench that President Trump can now fill with conservatives.”