The news that the two-term Representative is throwing his hat in the ring is being greeted enthusiastically by Republican officials around the state, who see Gardner as the strongest challenger yet to the incumbent.
Eight Republicans have already entered the Senate primary race, but Gardner has a higher national profile and deeper campaign pockets than all of them, with $875,000 already in his campaign warchest.
The Denver Post was the first to report Gardner's entry into the Senate race.
After news of Gardner's plans broke, one Senate candidate Weld County District Attorney Ken Buck, told the Greeley Tribune that he will drop out of the race and run for Gardner’s open Congressional seat instead.