President Trump is set to make his historic criminal trial a personality contest as he attempts to retake the White House. The former president’s attacks on the presiding jurist, Judge Juan Merchan, are just one part of his attempts to convince voters that he is the victim of a weaponized justice system. 

On Monday, Mr. Trump will appear in a Manhattan courtroom for jury selection in his criminal hush money trial, which marks the first time in American history that a former president has been charged with violating the law.

He has ramped up his attacks in recent days, even after Judge Merchan placed a gag order on the defendant.

“Judge Juan Merchan, perhaps the most highly conflicted Judge in New York State history, only gave us a short period of time to read and study hundreds of thousands of pages of documents,” Mr. Trump wrote in a Truth Social post on Sunday. “They could have started this Fake Biden Trial many years ago, not right in the middle of my campaign for President, and time would not be a problem.”

In another screed, the 45th president asked his followers to rank Judge Merchan among the other judges who have presided over Mr. Trump’s legal troubles. 

“Who is the WORST, most EVIL and most CORRUPT JUDGE? Would it be Judge Arthur Engoron, Judge Lewis Kaplan or, could it be that my current New York disaster, Judge Juan Merchan, is the WORST?” the president asked, referring to Judge Engoron, who levied a nearly $500 million fine against Mr. Trump in the state civil fraud case, and Judge Kaplan, who presided over E. Jean Carroll’s sexual assault and defamation lawsuit. 

“They are all from violent crime (without retribution!) filled New York, are really bad Judges, are extraordinarily conflicted and unfair, and most obviously to all, suffer from a rare but very lethal disease, TDS, commonly known as TRUMP DERANGEMENT SYNDROME,” he continued.

Mr. Trump also went after Judge Merchan at a rally in Pennsylvania on Saturday. “On Monday in New York City, I will be forced to sit fully gagged,” Mr. Trump said. “I’m not allowed to talk. Can you believe it?”

On March 26, the judge imposed a “tailored” gag order for the case, barring Mr. Trump from attacking his former lawyer, Michael Cohen, who has provided information for the prosecution, and the adult film star with whom Mr. Trump had an affair, Stormy Daniels, whose real name is Stephanie Clifford. 

“It is without question that the imminency of the risk of harm is now paramount,” Judge Merchan wrote in his order. The jurist has not barred Mr. Trump from attacking the judge himself or Manhattan’s district attorney, Alvin Bragg, who brought the charges and will now make his case. 

Mr. Bragg’s office has already complained that Mr. Trump is violating the gag order. That complaint was filed after Mr. Trump complained in an Easter Truth Social post about the “CROOKED AND CORRUPT” prosecutors and judges who are involved in his various legal cases. 

“This Court should make abundantly clear that the March 26 Order protects family members of the Court, the District Attorney, and all other individuals mentioned in the Order,” Mr. Bragg’s letter to Judge Merchan said. “Such protection is amply warranted.” 

The “threatening and alarming remarks about family members of trial participants” raise “objectively reasonable concerns about their safety,” the letter continued. In a competing letter, Mr. Trump’s lawyers said he did not violate the letter of the order. 

The hush money trial is expected to last between six and eight weeks, according to prosecutors. 

Cohen — who served time in prison for his role in the hush money scheme and has admitted to being the facilitator of a six-figure payment to Ms. Clifford in the run-up to the 2016 election — is expected to be a key witness in Mr. Bragg’s prosecution of the former president. 

Other potential witnesses include Ms. Clifford and chief executive of American Media, Inc., David Pecker, who was involved in a number of “catch and kill” schemes to bury negative stories about the then-presidential candidate. Mr. Pecker allegedly used $30,000 of his company’s money to pay off a Trump Tower doorman who was going to tell reporters about a purported illegitimate child Mr. Trump had with a mistress. Mr. Pecker also allegedly paid $150,000 to a former Playboy star, Karen McDougal, who claims she had an affair with Mr. Trump.

Mr. Trump announced on Saturday that he would “absolutely” testify at the trial if given the chance. He did testify during the lawsuit brought by Ms. Carroll, and took the witness stand in the civil fraud case, where he used the lectern to attack his rivals. 

In an interview with Politico, Cohen warned the public and the prosecution that Mr. Trump will throw as many punches as necessary to avoid jail time. 

“There is a ton of misinformation, disinformation, malinformation that has been put out there by Trump and acolytes,” Cohen said. “Trust me: I’ve been there. I know what he’s intending to do, and he’s not bluffing,” the former lawyer said of the personal attacks Mr. Trump employs.