Just when you thought this year’s campaign season in Colorado would be more of the same—a GOP menagerie of characters trying to unseat bruised but well-funded Democratic incumbents, with the net results remaining unchanged—Cory Gardner has thrown a wrench into the whole thing.

This week, Gardner, the District 4 Congressman who was a lock to retain his seat in the United States House of Representatives, decided to see how his long-held stature as one of the Colorado Republican party’s rising stars might play on a bigger stage when he announced that he was abandoning his House race to run against Mark Udall for our senior Senate seat.

Before Gardner’s entry, the GOP primary was expected to be a cannibalistic free-for-all that would burp up whichever candidate had the fewest bite marks to face the incumbent. Udall’s $5 million war chest eclipsed that of the other candidates put together—Amy Stephens, Owen Hill, Ken Buck, and three minor aspirants.

Now, everything’s changed. Stephens has already dropped out, and Buck will now run for Gardner’s vacated seat. (He’s expected to easily win the conservative Eastern plains district.) Only the Tea Party darling Hill is still in the race, and is grousing about supposed “backroom deals” he says Gardner cut with party officials.

With control of the U.S. Senate up for grabs in 2014, this will be one of the most watched races in the country. We can expect a record amount of dollars and endless partisan ads to flow through the state between now and November, because even if Gardner becomes the only Republican to win a hotly contested Colorado race, the prestige of the Senate seat alone will spur talk of the state GOP finally emerging from its multi-cycle hibernation.

Senator Udall is vulnerable. Despite his current fundraising advantage (which may evaporate), his office has spent the past few months fending off accusations that it tried to intimidate state insurance officials into fudging Obamacare enrollment and cancellation numbers. Gardner made that one of his talking points—albeit a disingenuous one—before he even entered the race, and every GOP candidate in the country will be hammering on the Affordable Care Act (whether or not it’s actually working) as long as it keeps scoring points.

For now, Udall will keep playing defense. But before we anoint Gardner as the favorite, he’ll have to prove that the extremely conservative voting record he’s leveraged so well along the Eastern Plains can resonate in a statewide race. For example, he has received an A+ rating from the NRA and also has supported the retrograde “personhood” Constitutional amendment that Colorado voters have repeatedly rejected by wide margins.

In short, what was already a lively political year in Colorado just became downright manic. Such is life in this perpetual swing state. It’s intriguing and occasionally aggravating, but it’s never dull.

—Image courtesy of Shutterstock.

Follow 5280 articles editor Luc Hatlestad on Twitter at @LucHatlestad.