(CNN) - Mitt Romney will not attend a Labor Day forum in South Carolina organized by conservative kingmaker Sen. Jim DeMint, who endorsed Romney's run for president four years ago.
Romney spokesperson Ryan Williams, citing scheduling conflicts, said the candidate will instead spend the day in New Hampshire, sending another signal that the former Massachusetts governor is not focusing on the early Southern primary state like he did in 2008. He was not previously listed as attending the event by the organizers.
Last week CNN confirmed Texas Gov. Rick Perry, Minnesota Rep. Michele Bachmann, Texas Rep. Ron Paul and businessman Herman Cain will participate in the Palmetto Freedom Forum, to be held Sept. 5 in downtown Columbia. Former House Speaker Newt Gingrich accepted the invitation Tuesday becoming the fifth participant, the campaign confirmed via Twitter.
Also invited were two Republicans still flirting with a bid: former Alaska Gov. Sarah Palin and former New York City Mayor Rudy Giuliani. Though unexpected, if they choose to accept they have until 5 p.m. Wednesday to indicate they will participate.
But event organizers - a small group of well-connected DeMint supporters calling themselves the "Keep Your Powder Dry Caucus" as they search for a 2012 candidate to get behind - did not invite two declared candidates, former Pennsylvania Sen. Rick Santorum and former Utah Gov. Jon Huntsman.
Organizers said early on that to be invited, a candidate must surpass the five percent threshold in the RealClearPolitics average of national polls. Santorum and Huntsman have yet to do so.
The forum, officially titled the "American Principles Project Palmetto Freedom Forum," will be fronted by DeMint, Iowa Rep. Steve King and Robert George, a conservative legal scholar and the founder of the American Principles Project.
Candidates will take turns fielding questions from the trio of panelists for roughly 20 minutes at a time.
According to organizers, candidates will be asked to "engage in a thoughtful, substantive discussion of their stances on critical issues facing our country."
- CNN Political Reporter Peter Hamby contributed to this report.