In a surprise decision, Republican Rep. Cory Gardner has decided to jump into the Colorado Senate race against incumbent Democrat Mark Udall. While there are other Republicans running already, Gardner gives the GOP an upper-tier candidate in a race that has not been considered competitive until now. The news was first reported by the Denver Post .  

Gardner is considered a rising star with the Republican ranks, but also a member who is somewhat risk averse. Up to this point, it appeared that Gardner was not willing to give up his safe 4th District seat for a long-shot run against Udall in a very competitive state. But with public polling showing Udall in a tight contest against lower-tier foes such as 2010 GOP Ken Buck and the national environment still trending against Democrats, Gardner must have thought this was the time to run.  

State Sens. Owen Hill and Randy Baumgardner and state Rep. Amy Stephens were already running, along with Buck, before Gardner’s decision. The filing deadline is March 31.  

Gardner’s decision would also open up his House seat. But Mitt Romney won the 4th District with 58 percent in 2012 and John McCain won it with 56 percent in 2008, so it would not start as a great Democratic opportunity.  

There is no guarantee that Gardner will be the GOP’s Senate nominee, but this race should no longer be considered Safe for the Democrats. We’re changing the Rothenberg Political Report /Roll Call rating of Colorado’s Senate race to Democrat Favored , but it could get much more competitive very quickly.