Gardner’s change of heart shakes up Colo. Senate race
© Greg Nash

Democratic Sen. Mark UdallMark Emery UdallSenate GOP rejects Trump’s call to go big on gun legislation Democratic primary could upend bid for Colorado seat Picking 2018 candidates pits McConnell vs. GOP groups MORE’s path to reelection just got a lot rockier in Colorado with the surprising news that GOP Rep. Cory GardnerCory Scott GardnerSenate GOP urges Trump administration to work closely with Congress on NAFTA Trump makes Manchin top target for midterms Wyden: I object to Trump’s DHS cyber nomination over demands for Stingray information MORE plans to challenge him in the Senate race.

Multiple sources confirmed to The Hill that Gardner will make the announcement in a few days, reversing his decision in May not to challenge the Democratic incumbent.

Gardner’s change of heart is a coup for Republicans and expands an already daunting Senate map for Democrats. His decision finally gives the GOP an A-list candidate in a race they had hoped to make competitive.

While Colorado had been on the bubble of competitive contests, Gardner’s entrance — if he wins a June 24 primary — has the potential to vault the race into the top tier and further help the GOP flip the six seats they need to win a Senate majority.

Dick Wadhams, a Republican political strategist and former state GOP chairman, said he woke up Wednesday morning and had no idea Gardner would jump in the race, but now that he has, the congressman’s decision has made it a “very winnable one.”

“I think Cory Gardner is a game changer, not only in the Senate race, but across the board in this election cycle for Colorado Republicans, because he is the kind of Republican candidate we have desperately needed for several election cycles,” Wadhams said.

“I was really concerned that Colorado Republicans were on the verge of being irrelevant in statewide races. Republicans have needed someone they can rally around.”

Independent state political analyst Eric Sondermann said he expected the political landscape in the state to further shift in the next few days, as Republican candidates in both the Senate and other races decide where to run.

“It’s really the ultimate testimony to the changing political landscape in Colorado and across what I call purple America, that somebody like Cory Gardner — who has the luxury of sitting and waiting and picking his time, and who has the reputation of being somewhat risk averse — would decide to stake it all this year against a name-brand incumbent Democrat who, up until maybe two months, was considered a lock,” Sondermann said.

Gardner’s decision has already altered the race. 2010 Senate nominee Ken Buck plans to announce that he’s dropping his Senate bid to run for Gardner’s House seat, a Colorado Republican with knowledge of Buck’s plans tells The Hill.But state Sen. Owen Hill, who has received some Tea Party backing, said he’d be staying in the race — and he’s “more enthusiastic than ever” about running.

He said Gardner had tried to convince him to step out of the race a few weeks back, but Hill refused, and said such “insider trading” was hurtful to the Republican Party.

“I’m not surprised at all” Gardner’s in, he told The Hill. “A couple of weeks ago, Cory said he wanted me to get out of the race, and I called him out at the time. I said, ‘This is an insider deal with Ken Buck to try to switch races, and this is the exact kind of insider trading by the Republican establishment that keeps losing us races.’

First elected in 2010 by knocking off Democratic Rep. Betsy Markey, Gardner initially passed on the race last year, many believed, because he didn’t want to give up what was now a solidly Republican congressional seat following the 2012 redistricting and jeopardize a promising career in the House.

Gardner starts the nine month sprint at a huge fundraising disadvantage. At the end of the year, he had just $877,000 in his campaign account compared to Udall’s $4.7 million war chest.

Sondermann said, “The fact that he would give up a very safe congressional district to roll the dice on the Senate race tells me that Republicans believe this is their moment.”

While Udall still remains the favorite, recent surveys showed his approval ratings were falling in the swing state. A Quinnipiac University poll earlier this month showed voters were split on whether Udall should get another term.

Facing even weak GOP challengers, he only had a slim lead. In a match-up againstBuck, he only took 45 percent to Buck’s 42 percent. Udall led Hill by 5 percent, with 44 percent support, and topped businessman Jaime McMillan by 7 percentage points, with 45 percent support. He lead state Rep. Amy Stephens by just 43 percent to 41 percent.

President Obama could especially be a drag for Udall in Colorado. Though he carried the state by 5 points, 51 percent to 46 percent in 2012, his approval ratings have cratered there since, in large part due to the unpopularity of his signature healthcare legislation.

In the Quinnipiac poll, 59 percent of Coloradans said they disapprove of the president, and 60 percent oppose his healthcare law.

In fact, 40 percent of voters said they would be less likely to vote for Udall if Obama campaigned with him in the state.

Democrats were already on the attack against Gardner, tying him to the Tea Party in a statement on his upcoming decision.

“Despite his slick Washington insider demeanor, Cory Gardner is just as extreme as Ken Buck, Amy Stephens and all the others. Gardner wants to decimate Medicare, slash education and even make common forms of birth control illegal,” said Democratic Senatorial Campaign Committee deputy executive director Matt Canter. “Gardner’s Washington friends may have helped him in the Republican primary but won’t be able to hide his reckless and irresponsible Tea Party agenda from mainstream Coloradans.”

Russell Berman and Cameron Joseph contributed to this report.

--This post was updated at 7:50 a.m.