Lewis was left out of NBC's "Meet the Press" forum with Talent and McCaskill last Sunday morning.

Wednesday night, Lewis handed out pamphlets outside Clayton High School in St. Louis County, the site of the latest Talent-McCaskill forum.

"The two main parties have things pretty well sewn up, and it's just hard to get into anything with them if they choose to keep you out. And that's what's going on now," complained the Libertarian Party candidate, Frank Gilmour. "There's no reason for them to be holding debates unless all the candidates are present."

The most recent poll of likely voters shows McCaskill and Talent in a virtual tie. Many online polls also exclude Gilmour and Lewis.