The Post reports: “Senate Republicans have scored an unexpected recruiting coup, with Rep. Cory Gardner (R) opting to challenge Sen. Mark Udall (D-Colo.) this year, according to a person with knowledge of his plans. Gardner, who is considered the state’s top GOP rising star, previously said he would not run for Senate and would instead seek reelection in November.” As important, failed Senate candidate Ken Buck has opted for the House race, avoiding a bitter primary and winning the gratitude of his party.

President Barack Obama talks about the events in Colorado in Fort Myers, Fla., Friday, July 19, 2012. Obama said the tragic movie theater shooting in Colorado that left 12 people dead is a reminder that life is fragile. He says the event "reminds us of all the ways that we are united as one American family." (AP Photo/Alan Diaz) President Barack Obama talks  (Alan Diaz/Associated Press)

This is a huge improvement for the GOP and puts yet another Senate seat in play. Udall, you will recall, has run into real trouble with a scandal relating to his bullying of state Obamacare exchange employees. Between that and his support for the Obama agenda, he had only a single digit lead in polls before the Gardner announcement. Moreover, Obama is polling horribly in the state, below 40 percent in some surveys in a state he won in 2012.

In a quick survey of about a half-dozen House offices and several third party groups I heard nothing but very upbeat reactions. “A fantastic development,” said one aide. Another: “Hurts to lose him in the house, but good get for Senate Rs.” From a leadership aide: “He is widely liked and respected by the Republican conference, and he’s been an effective advocate for Colorado. It’s bittersweet, but he’s the best candidate to take on Mark Udall on the economy and Obamacare.” From one money-raising group: “He’s leaving a safe district and he’s on a leadership track. This is VERY gutsy and he must really want it, which means he’s going to work hard.” Others described Gardner as the best-case scenario for the GOP.

According to one insider, Gardner has about $1 million already in his House coffers that he can transfer to a Senate campaign. He has a 69 percent rating from the conservative Club for Growth, putting him in about the middle of the GOP conference.

Larry Sabato immediately changed the Senate rating from “likely Democrat” to “leans Democrat.” The Rothenberg Political Report likewise moves the race in the GOP’s direction: “Gardner gives the GOP an upper-tier candidate in a race that has not been considered competitive until now. . . . 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.” He, therefore, also changed the rating from “safe” to “Democrat favored.”

When it rains it pours, I suppose, for the party on the wrong side of a possible wave election. Better candidates decide to run when they see opportunity; donors in turn open their wallets. Each time a new competitive candidate pops up (e.g. Ed Gillespie in Virginia), it makes it that much more difficult for the Democrats to play defense. (There are just so many states Bill Clinton can get to in an effort to save Democrats endangered by Obamacare.) And GOP voters, seeing a real chance to take the Senate, exercise more care in primaries to find electable candidates, understanding that a “protest” or “purity” vote may mean losing a Senate majority that is clearly within grasp.

No wonder Democrats are frantic to make an immigration deal now. They see what’s coming.