The decision, first reported by the Denver Post, that Congressman Cory Gardner (R-CO) will run for Senate against incumbent Democrat Mark Udall could determine control of the Senate in 2015.
Republicans have long been aiming to win the six seats necessary to take back the Senate this year. While the map is very favorable for the GOP with open Democratic-held seats in deep red states like Montana and West Virginia as well as vulnerable Democratic incumbents in other solidly Republican states like Louisiana, Arkansas and Alaska, it still required Republicans to essentially run the table to make Mitch McConnell the next Senate Majority Leader----especially with Democrats competing for an open GOP-held seat in Georgia and mounting a strong challenge to McConnell in Kentucky. The vulnerability for the GOP had been a lack of candidates in traditional swing states. But that's not the case anymore with Gardner's candidacy.
Gardner's entry into the race, along with former lobbyist and RNC chair Ed Gillespie throwing his hat into the ring to run against first-term Mark Warner in Virginia, mark a massive expansion of the 2014 playing field. In a December poll, Udall had only been narrowly favored against Ken Buck, the losing GOP Senate nominee in 2010 who was considered a gaffe-prone exemplar of the worst kind of Tea Party candidate. Gardner, widely considered a rising political star, makes the race significantly more competitive for the GOP, particularly with Buck dropping out of the Senate race to run for the House seat that Gardner is vacating.
Colorado is still a swing state and, at best, will be a toss up for the GOP in November. But his entry still shakes up the race entirely. The non-partisan Rothenberg Political Report immediately shifted the race from Safe Democratic to Democratic Favored while warning "it could get much more competitive very quickly."
Gardner's entry into the race expands the playing field for the Republican Party by one more state and makes it that much more likely that the GOP will control both chambers of Congress in 2015.