CNN — Kamala Harris is officially the Democratic presidential nominee, but Donald Trump is continuing to describe the vice president’s elevation to the top of her party’s ticket as “unconstitutional” and accusing her of taking part in a “coup.” No serious effort to challenge Harris’ status as the Democratic nominee is underway. But some of Trump’s critics warn that the former president could be laying the groundwork to question the outcome of the 2024 election if he loses a second time. Democrats are set to gather next week in Chicago for a national convention at which they’ll rally around Harris...