Leaders of 21 state Tea Party groups, representing about 10,000 people, said Sunday they have been betrayed by Tom Tancredo and in an open letter beseeched the former congressman not to run for governor as a third-party candidate.

Tancredo has given Republican gubernatorial candidates until noon today to commit to pulling out of the governor’s race after the primary if polls show the winner trailing Democrat John Hickenlooper.

If that doesn’t happen, Tancredo says, he’ll run for governor as the American Constitution Party candidate.

Tancredo’s declaration last week — the most recent drama to plague the state’s GOP gubernatorial primary — sparked anger among the diffuse Tea Party groups around Colorado.

Those leaders say it was Tancredo who had always urged them to work within the Republican Party, rather than splinter it. He has long inspired fierce loyalty from the groups because of his stance on illegal immigration.

“Together our groups strongly urge you to reconsider, withdraw your ultimatum, stay in the Republican Party, let the process play out for the governor’s race,” said the letter signed by 21 active Tea Party and 9.12 groups. “In other words, to trust and respect the newly awakened, energized and informed voters of Colorado.”

The letter said that if Tancredo carries out his promise, it means an “impending disaster, assuring victory for Mayor Hickenlooper and the liberal agenda in Colorado for at least four more years.”

The letter also cited an unscientific survey of Tea Party members that suggested 66 percent would not vote for Tancredo in the governor’s race.

Don Rodgers, leader of the Pikes Peak Patriots in Colorado Springs, said Tancredo has contradicted himself.

“He said a third party or a minor party would be suicidal. He encouraged us to get involved, and we had thousands of people who did just that,” Rodgers said. “They became delegates. They did it through the process. Because Tom didn’t like who they had chosen, he gave us this ultimatum.”

Fallout after ultimatum

Tancredo said Sunday he received the letter and more than 100 separate e-mails. He called Tea Partyers new members of “the establishment.”

Asked about the letter he wrote to the grassroots’ groups in 2009, encouraging them to work together, he said, “it’s interesting that many of them chastised me at the time for encouraging party unity.

“I think they should use their energy to urge their candidates to accept this pledge and when they do, they don’t have to worry about me,” he said, noting he’s gotten many letters of support, as well. “I will not be a factor. I will walk away.”

GOP gubernatorial hopeful Scott McInnis is weathering allegations of plagiarism after The Denver Post reported portions of a water essay he authored were nearly identical to an essay written by state Supreme Court Justice Gregory J. Hobbs.

McInnis’ primary opponent, Dan Maes, is considered weak by GOP-establishment types, yet won a majority of the votes at the state’s spring GOP convention among the grass roots.

“The ballots are out, let’s let the people have a say,” said Jennifer Bailey, president of the Western Slope Conservative Alliance, which signed the letter. “I think we’re all intelligent enough to weigh what’s gone on and let’s let the people speak.”

State GOP chairman Dick Wadhams, who issued a similar plea last week, said he sympathized with the Tea Party groups and agreed with them.

“This deadline is a phony deadline created by him only so it will give him some superficial cover to announce his candidacy,” Wadhams said. “This letter from 9.12 leaders clearly shows the only person who thinks this is a good idea is Tom Tancredo.”

Allison Sherry: 303-954-1377 or asherry@denverpost.com