DENVER -- Several high profile Republicans are pulling their support from Republican gubernatorial candidate Dan Maes.

Former U.S. Sen. Hank Brown rescinded his endorsement on Wednesday because of concerns about Maes' credibility. Brown said he's looking for a new candidate to support.

Brown cited inconsistencies in Maes explanation of why he was fired from a Kansas law enforcement agency as the breaking point for his endorsement.

"I suppose the most difficult thing for me was that he had not been an undercover policeman in Kansas," said Brown.

When questioned about that, Maes fired back. "'Some have said you've exaggerated your past. Have you?' asked 7NEWS. No, I haven't. As a matter of fact I'll stand by my resume, which is online. I'll stand by my employment. Those who claim I've exaggerated my past don't seem to be in the Dan Maes camp too much," said Maes.

"I sympathize for him and his family, but I think Coloradans expect more," said Brown.

Brown said if Maes stepped aside, there would be plenty of qualified candidates to fill the void, but he wouldn't be one of them. "No. I've served my time and had that opportunity," said Brown. "If there should be an opening, they'll find a good candidate, but it won't be me."

All this follows reports that Maes is backpedaling on a claim that, as a police officer 25 years ago, he worked "undercover" with the Kansas Bureau of Investigation.

Maes backed off that account after the head of the Kansas Bureau of Investigation told the Denver Post it has no record of Maes working with the agency during his stint as a police officer in Liberal, Kan., from 1983 to 1985. (Read more about that story.)

But on Thursday, Maes posted a new statement on the controversy:

"I stand by everything I have said. When you get the media and the machine out of the way and the peoples (sic) voices are heard, we win. Do not be deceived by the word games and manipulation by the media. We are in the 4th quarter of the game and we must dig deeper than ever into our souls to find the strength to fight to the end. Do not waiver.(sic) This is all part of the journey."

Former congressman Bob Beauprez also said Maes should bow out.

Beauprez gave Maes credit for all that he has accomplished so far.

"The critical element in any campaign isn't whether all the voters agree with you 100 percent of the time. It's if they believe you and trust you. And that's the part that seems to be evaporating on Dan real quickly," said Beauprez. "And if he's really got the best interests of the party and the state at heart, he could take the high road, do the noble thing and that would be to step away."

Beauprez said if a candidate were to step in, the campaign would need to go from zero to 100 immediately.

He said he would consider stepping in if that's what the party chose. "If someone wants to make the call, I'll take the call seriously and we'll think about it then. But, it's too early to be talking about that," he said.

Former Colorado Senate president John Andrews told 7NEWS he called Maes on Thursday to withdraw his endorsement and Andrews said he urged Maes to end his candidacy for the public good.

"As a conscientious Republican who earlier voted for Dan, I cannot support a manifestly unfit nominee. He has flunked his job interview with the people of Colorado in the weeks since Scott McInnis faded. The party should cut Maes loose if he does not resign the nomination," Andrews said in a statement.

Andrews said he intends to write in a vote for Jane Norton for governor. Norton lost to Ken Buck in the Republican primary for the U.S. Senate seat.

"What I see is people trying to hijack the process," said Maes. "They can say my credibility is destroyed. I don't think it is at all."

Maes admitted Thursday support has dropped off. But he said he's not going anywhere.