On May 19, Robert F. Kennedy, Jr., appearing on television, pointed out that neither President Joe Biden nor former President Donald Trump are officially on any state’s ballot so far. That is because they haven’t been nominated yet, and they will not have both been nominated until late August. See this story. Of course CNN, the sponsor of the June 27 debate, considers Biden and Trump to have “qualified for the ballot in states with at least 270 electoral votes” because CNN knows it is extremely likely that they will be on the ballot.
Also Kennedy said he will be on the ballot in states with 301 electoral votes by the end of May.