After urging Mitt Romney to attend a Republican presidential forum in Des Moines this weekend, the head of Iowa's Family Leader group, which organized the event, said Tuesday that the former Massachusetts governor has "dissed" Iowa's social conservative base by declining to appear. "Mitt Romney has dissed this base in Iowa and this diss will not stay in Iowa," Bob Vander Plaats said in an interview with Fox News. "This has national tentacles. ... This might prove that he is not smart enough to be president, " Vander Plaats continued, clearly miffed. "I think what will happen is what happened in 2008. He's been in this position before. He's been on top of polls only to find his campaign tanking and sucking air." The Romney campaign confirmed that Romney is returning to Iowa next week but will not be participating in the event to be attended by presidential hopefuls Newt Gingrich, Rick Perry, Herman Cain, Ron Paul, Michele Bachmann and Rick Santorum. Instead, Romney will take part in a December event arranged by former Arkansas governor, presidential candidate and current Fox News host Mike Huckabee. The Family Leader forum will focus on issues such as traditional marriage, life and limited government, according to organizers. Vander Platts said he thinks Romney's absence may lead the Iowa social conservative base to coalesce around an alternative candidate to Romney. "I think this is a real opportunity for Newt Gingrich, Rick Santorum, or Michele Bachmann to beat Mitt Romney in Iowa," said Vander Plaats, a former gubernatorial candidate and 2008 Huckabee backer. "If Romney loses Iowa, I think it will be a huge dent to his campaign. It will be just like fours years ago, and New Hampshire will be up for grabs. Everyone knows he won't win South Carolina and Florida. He will not win in the South," he said. Frank Luntz, a Fox News contributor, will be the host at the Saturday roundtable event.