A large conservative advocacy group aligned with the Tea Party movement stayed out of the Delaware Senate race over concerns about Republican Christine O'Donnell's candidacy.

"We stayed out of that race because we're not convinced that Christine O'Donnell can win," Matt Kibbe, the president of FreedomWorks, told reporters Monday.

O'Donnell had a slim lead over Rep. Mike Castle (R-Del.) in one of the final polls before voting starts Tuesday. She was ahead 47-44 in a Public Policy Polling survey of likely Republican primary voters conducted Sept. 11-12. That lead, however, falls within the poll's margin of error.

Kibbe said if Castle loses, it raises the question, "does he deserve to win the general?"

"What the Tea Party activists have really asked for is an open primary where their candidates get a chance to run and compete and prove themselves or lose," he said.

During the breakfast sponsored by The Christian Science Monitor, reporters asked Dick Armey, who chairs FreedomWorks, if it was better to lose with a Tea Party candidate than win with a mainstream Republican. "No, and I don't think the Tea Party activists would give you a different answer," he said. "Massachusetts and New Jersey proves that."

The Tea Party movement has been growing in size and influence since it helped influence the outcome in a string of Republican Senate and House primaries. Kibbe said the next step for the national coalition of anti-government activists was to pursue "fiscal conservative policy."

"The next step in the growth of the Tea Party movement is finding legislative champions ... that develop a positive set of ideas that actually become real fiscal, conservative policy," he said. "And that's not an easy thing to do."

--Updated at 12:09 p.m.