DENVER -- GOP gubernatorial candidate Dan Maes said a round of automated phone calls telling registered Republicans he's dropping out of the race and endorsing his GOP opponent are false.

"Coloradans are sick and tired of business-as-usual politicians and these business-as-usual cheap shots," said Maes in a news release send to 7NEWS. "My campaign has been focused on a positive, conservative message from the beginning, and dirty tricks in the 11th hour are a clear sign that my message is resonating with voters."

The news release said the robocalls claim to be from Maes campaign headquarters, but contain no information suggesting their source or funding.

The Maes campaign said it was told about the calls by several supporters late Tuesday night.

The campaign has notified the State Attorney General's office about the false calls.

"I’m proud to notify the citizens of this state that I’m in this race for the long haul, and I have every intention of becoming Colorado’s next governor," said Maes.

Maes and his primary opponent, Scott McInnis, have both been urged to pull out of the race by former GOP congressman Tom Tancredo, who switched to the American Constitution Party so he could run against Democratic candidate John Hickenlooper.