Here's a list of everyone who plans to participate, courtesy of the New Hampshire Union Leader, one of the sponsors. And here's what to watch:
1. Trump won't be there. But he could still leave an impact.
The candidate sucking up all the oxygen in the race in recent weeks, real estate mogul Donald Trump, has said he is unlikely to get the Union Leader endorsement and will not be participating. But it's possible other candidates will mention him or face questions about him. Who cozies up to him? Who keeps their distance? And who ignores him altogether? The answers to these questions will provide some clues about how candidates plan to approach him come Thursday. There are risks (you may well end up in a nasty public back-and-forth with him) and upsides (you may get more earned media attention in the campaign as a result) to both ignoring and engaging Trump.
2. Who will be there in person versus who won't.
The Senate plans to hold a key vote Monday on defunding Planned Parenthood, a move many Republican candidates have been championing. The Union Leader reports that will keep Sens. Ted Cruz (Tex.). Rand Paul (Ky.) and Marco Rubio (Fla.) in Washington, where they will participate remotely. Sen. Lindsey O. Graham (S.C.) plans to be there, the Union Leader reported. Look for senators not appearing in person to remind voters of the work they are doing in Washington in the debate over abortion rights.
3. To engage or not to engage?
Just because this is not a debate doesn't mean some candidates will not call out others. While some hopefuls have remained studiously committed to their own messages, others have not been shy about throwing verbal punches. Any direct or indirect criticism and responses will receive a lot of attention coming out of the event. The question is who, if anyone, wants to go on offense at this very early stage of the race.
Any gaffes or surprising comments will be magnified. This is a prime time event in a key early state where candidates will inevitably be judged alongside on another. Missteps will probably appear to be bigger deals than they actually are. "No news is good news" is a safe motto for most of the top tier candidates today.