Former President Donald Trump, who according to polls is the heavy favorite to win the Republican presidential nomination, has said he will skip all debates. Indeed, he was not present at the first debate. Trump may host a rival event at the same time as the next debates, as he did in August when he was interviewed by former Fox host Tucker Carlson.
The Democrats have not organized a single primary debate so far. The two main challengers to incumbent President Joe Biden, Robert F. Kennedy and Marianne Williamson, have repeatedly asked for this. If the party does organize debates, there is very little chance that Biden will participate: no sitting president has participated since 1948, when the first primary debate was held.