Last night’s news that Republican Marc Holtzman did not gather enough vaild signatures to make it onto the primary ballot may turn out to be the single most important day of the 2006 election season.

With Holtzman out of the race, Republican Bob Beauprez can now focus his sights solely on Democrat Bill Ritter. With Holtzman in the race, Beauprez would have had to expend a lot of time, energy and money to beat Holtzman in the August 8 Republican primary, and Ritter would have been sitting there waiting with his nearly full warchest of campaign funds. If Beauprez had won the primary, he would also have depleted his bank account in the process; that’s not a huge problem because national money would have quickly refilled those coffers, but the bigger concern was the damage a bitter primary might have done in terms of image and issue positioning.

In a tough Republican primary, Beauprez was going to get beaten silly by attack ads exposing his every flaw. He would also have been forced to talk more conservatively about issues in order to appeal to the Republican right, which is a problem because Ritter can position himself to the general electorate as a moderate.

But now, everything changes. Beauprez can run as a moderate, just like Ritter, but as a moderate who is better-funded and more well-known. Beauprez is also a much more experienced campaigner than Ritter, and despite Democratic gains in recent years, Colorado is still a Republican-leaning state in terms of voter registration numbers.

That isn’t to say that Ritter is a big underdog, because I still think he and Beauprez are running about even if the election were tomorrow. But two days ago Ritter was the clear favorite; he’s not anymore, and it’s because of what another Republican candidate didn’t do.