A US judge dismissed one of Donald Trump’s criminal cases on Monday, handing the Republican presidential candidate a major legal victory just hours before he was due to reveal his vice presidential running mate.

The decision by a Trump-appointed judge comes two days after the former president survived an assassination attempt at a Pennsylvania campaign rally by a gunman whose motive remains unknown. US District Court Judge Aileen Cannon ruled that the prosecutor who charged Trump with mishandling classified documents was unlawfully appointed to his role.

Meanwhile, Trump was expected to formally announce his vice presidential pick at the 2024 Republican convention in Milwaukee, according to a source who spoke on condition of anonymity. Republicans will nominate the candidate at approximately 4:30pm ET (2030 GMT), though Trump could reveal his pick before then.

Leading contenders include Ohio US Senator JD Vance, Florida US Senator Marco Rubio and North Dakota Governor Doug Burgum, all of whom are slated to speak at the convention this week.

Trump is due to formally accept the party’s nomination on Thursday to challenge Democratic President Joe Biden in the Nov 5 election.

Trump, 78, and Biden, 81, are locked in what opinion polls show to be a tight election rematch. Trump continues to falsely claim that his 2020 loss to Biden was the result of widespread fraud and has not committed to accepting the results of the election were he to lose.

In the wake of the assassination attempt, Trump said he is revising his acceptance speech to emphasize national unity, rather than highlight his differences with Biden.

“This is a chance to bring the whole country, even the whole world, together. The speech will be a lot different, a lot different than it would’ve been two days ago,” Trump told the Washington Examiner.

Trump said that following the judge’s decision on Monday dismissing the documents case, his other outstanding prosecutions should also be thrown out. He is still awaiting trial on two cases – a federal prosecution in Washington and a Georgia state prosecution – for his attempts to overturn his 2020 election defeat.

The July 1 Supreme Court ruling that he has immunity for many actions he took as president could hamstring both those cases.

Trump is also due to be sentenced in New York in September for trying to cover up a hush-money payment to porn star Stormy Daniels in the weeks before his 2016 election victory.

“This dismissal of the Lawless Indictment in Florida should be just the first step, followed quickly by the dismissal of ALL the Witch Hunts,” Trump said on his Truth Social site on Monday, also referencing the prosecutions of hundreds of his supporters who stormed the US Capitol on Jan 6, 2021.

No place for violence

Biden is trying to bring the temperature down after months of heated political rhetoric.

“There is no place in America for this kind of violence, for any violence ever. Period. No exceptions. We can’t allow this violence to be normalized,” he said of the assassination attempt in a televised address from the White House on Sunday.

The shooting on Saturday whipsawed discussion around the presidential campaign, which had been focused on whether Biden should drop out following a halting June 27 debate performance.

Nearly two dozen of Biden’s fellow Democrats have called on him to end his reelection bid and allow the party to pick another standard bearer. That debate has been placed on hold in the wake of Saturday’s shooting.

The focus this week will be squarely on Trump.

Having consolidated party control, Trump could seize on the prime-time opportunity to deliver a unifying message or paint a dark portrait of a nation under siege by a corrupt leftist elite, as he has done at times on the trail.

Trump has frequently turned to violent rhetoric in his campaign speeches, using the word “bloodbath”, labeling his perceived enemies as “vermin” and “fascists,” and accusing Biden without evidence of a conspiracy to overthrow the United States by encouraging illegal immigration.

Biden has often warned that a Trump victory in November would erode the United States’ democratic system. Some Republicans say those comments helped create the conditions for the shooting.

Investigators say they have been unable to identify an ideology that may have inspired 20-year-old Thomas Matthew Crooks to shoot at Trump from a rooftop outside a campaign event.

Biden ordered an independent review of how the gunman, who was shot dead by agents moments after opening fire, could have come so close to killing or severely wounding Trump despite the heavy security provided by the Secret Service at Saturday’s event in Butler, Pennsylvania.

The FBI said that Crooks’ social media profile contained no threatening language, nor had they found any history of mental health issues. They said he acted alone.

Crooks worked as a nursing home aide near his hometown of Bethel Park, Pennsylvania. He graduated high school with a reputation as a bright but quiet classmate. His guidance counselor described him as “respectful” and said he never knew Crooks to be political.