evidence: Harris flew to Wilmington, Delaware, where Mr. Biden stationed his 2024 campaign headquarters, to thank campaign staff. After he dropped out, she assumed his campaign operations. [...] Republican House Speaker Mike Johnson on Monday said he didn't think the dynamics of the 2024 race changed after President Biden dropped out of the race. But Johnson suggested that changing the nominee could "violate the rules" in some states, and he said he expects there will be "litigation." [...] Vice President Kamala Harris has emerged as a top contender to replace President Biden at the top of Democratic ticket following his historic decision to withdraw from the 2024 race for the White House.