President Trump railed Wednesday against a Senate tradition granting senators a sort of veto over judicial and U.S. attorney picks within their home states, saying it’s preventing him from installing conservative judges and hard-charging prosecutors in some Democrat-dominated places.

Mr. Trump took to social media to demand that Sen. Charles E. Grassley, the chamber’s most senior Republican and chairman of the Judiciary Committee, stop respecting the tradition, known as the “blue slip” policy, that allows the home-state veto.

“Chuck Grassley, who I got reelected to the U.S. Senate when he was down, by a lot, in the Great State of Iowa, could solve the ‘Blue Slip’ problem we are having with respect to the appointment of Highly Qualified Judges and U.S. Attorneys, with a mere flick of the pen,” the president said.

Mr. Grassley, who actually won his 2016 and 2022 reelections quite handily, bristled at the attack.

“I was offended by what the President said, and I’m disappointed that it would result in personal insults,” he said.

He said he doubted voters cared about the blue slip issue, but he said they should care about senators’ ability to use it to shape the federal judiciary and “the U.S. Attorneys who ensure law and order is enforced.”

The president’s history of blue slips was also slightly off-kilter.

Democrats respected the blue slip tradition when it came to district court picks, whose jurisdiction is always constrained to a single state or a part of a state. But Democrats did not respect the tradition when it came to circuit court nominations, which span multiple states.

That’s similar to how Republicans played it when they controlled the Senate during Mr. Trump’s first term.

Democrats this year have also been flexing the blue slip policy to block confirmation on some of Mr. Trump’s U.S. attorney picks. They say they’re following the lead of Vice President J.D. Vance, who they say started things when he was a senator from Ohio and forced roll-call votes on some U.S. attorney picks.

Mr. Trump said Senate Democratic leader Charles E. Schumer of New York and Democratic Sens. Mark R. Warner and Tim Kaine of Virginia, Cory Booker of New Jersey and Adam B. Schiff of California are all “sleazebags” for blocking “great Republican candidates.”

“Put simply, the President of the United States will never be permitted to appoint the person of his choice because of an ancient, and probably Unconstitutional, ‘CUSTOM,’ that if you have, even one person in the opposite Party serving in the U.S. Senate, he/she must give consent, thereby completely stopping the opposite Party’s Nomination,” Mr. Trump said.

Members of both parties have long used blue slips to deny opposing presidents some judicial nominees, but the practice has intensified in recent years as the battlefield over presidential action has shifted from Congress to the courts.

But Mr. Trump said he felt Republicans were getting out-maneuvered.

“The Democrats have broken this ridiculous custom on us, it’s time that we break it on them. Chuck, I know you have the Courage to do this, DO IT!” the president wrote.

Otherwise, he said, he will be forced to pick “a Democrat or, a weak and ineffective Republican” to get the approval of some Democratic senators.

Mr. Trump is currently battling to keep his acting U.S. attorney picks serving in New Jersey and Los Angeles over opposition from home-state Democrats.

Senate Majority Leader John Thune, South Dakota Republican, said Mr. Trump was wrong to denounce Mr. Grassley and the Senate’s handling of things.

“Chuck Grassley has done a great job. We just confirmed a circuit court judge last night. Emil Bove is now serving on the circuit court,” he said.

Mr. Bove, who served as Mr. Trump’s defense lawyer and who faced massive Democratic opposition, was confirmed Tuesday night to a lifetime appointment on a federal appeals court.

“I think the blue slip is something that’s been honored by both sides, and it hasn’t been violated by either side,” Mr. Thune said on Fox News. “And frankly, for that matter, it was used extensively during the Biden administration to block some really bad Democrat nominees to district judgeships.”

• Kerry Picket can be reached at kpicket@washingtontimes.com.