Democrats perturbed about Donald Trump’s lead in 2024 polling have long had a comforting hope to fall back on: that Trump, who is facing four criminal prosecutions, will likely become a convicted felon before Election Day — or even be sent to prison. That’s still possible — but it’s not as sure a bet as it once seemed. Delays have piled up in federal court proceedings in the District of Columbia case about Trump’s attempt to steal the 2020 election and the Florida classified documents case against Trump, making it unclear whether either case will go to trial before November....