Former GOP U.S. Rep. Tom Tancredo laid down the political gauntlet Thursday, challenging Republican gubernatorial candidates Scott McInnis and Don Maes to withdraw from the race, if polls show they can't win.Tancredo said "an unprecedented situation" has developed in the last two weeks in the race for governor.McInnis ran into opposition from members of his own party after he accepted responsibility for plagiarizing from a judge's work. Maes was criticized for refusing to release his tax returns and for campaign finance violations after he billed his campaign $44,000 for mileage over the past year and a half."The two candidates vying for the Republican nomination have, in my opinion, lost any hope of carrying out a successful campaign," Tancredo said.He said whoever wins the August Republican primary must step down and allow the Republican Party to appoint a viable replacement candidate to face "John Hickenlooper and the Obama-Pelosi smear machine.""Regardless of the outcome of the primary election on Aug. 10, on Aug. 11 the winner must agree to remove himself from consideration, if polling on that date shows that he is losing the race for governor. If either or both choose to ignore this request, and do not make a public commitment to this end no later than noon on Monday, July 26, I will announce on that day that I will seek the nomination of the American Constitution Party for governor of Colorado," Tancredo said in a written statement.The American Constitution Party's candidate, Benjamin Goss, declined to say Thursday whether he was stepping down voluntarily.Colorado Republican Party chairman Dick Wadhams said the party researched the bylaws for the American Constitution Party and determined replacing a candidate before the general election would be legal."Regardless of who our nominee is for governor after the primary, if Tom Tancredo carries through on his threat to run as a third party candidate, he will be responsible for the election of Denver Mayor John Hickenlooper as governor and for other races that will be imperiled as well," Wadhams said in a statement. "The American Constitution Party's platform calls for the elimination of congressional salaries and pensions. I assume when Tom Tancredo becomes that minor party's nominee, he will forego his own congressional pension and will reimburse American taxpayers for the ten years of congressional salary he drew."