Colorado Republicans finally have a dog in the fight for 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 (D) seat — two dogs, in fact, with more expected to come.

But the prospect of a contentious primary complicates the party’s chances at what they view as a potential pickup opportunity in the Senate.

Colorado state Sens. Randy Baumgardner and Owen Hill jumped into the GOP field this week after a number of higher-profile potential candidates — including 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 — took a pass. 

While Colorado voted Democratic in both of the last two presidential elections, Republicans note President Obama carried the state by less than 5 points in 2012. 

They also cite the 2010 Senate race, when Republican Ken Buck lost to Sen. Michael BennetMichael Farrand BennetSenate Dems to Mnuchin: Don't index capital gains to inflation GOP, Dem lawmakers come together for McCain documentary Overnight Health Care — Sponsored by PCMA — Trump official won't OK lifetime limits on Medicaid MORE (D) by less than 2 points, as another reason for optimism. 

Republicans say low turnout during a midterm year makes the terrain more favorable, especially considering growing backlash over the policies passed by the Democratic-controlled state Legislature and signed by Gov. John Hickenlooper (D).

Hickenlooper has signed stricter gun control measures, overseen the legalization of marijuana in the state and criticized the death penalty.

Colorado Republicans have suggested that, rather than tie Udall to national Democrats, they’ll work to link him to local lawmakers and Hickenlooper. They argue Udall is an extension of what they see as liberal overreach in the state. 

“There’s definitely growing backlash over some of the things that have happened in the Legislature,” said Owen Loftus, spokesman for the Colorado Republican Party.

“I haven’t seen people be this aware of what’s happening at the state level in years,” he added.

John Straayer, a political scientist at Colorado State University, said while the race is “Udall’s to lose,” he is sensing a growing backlash against the Democratic Legislature.

“Republicans think Democrats overreached badly on gun legislation, civil unions, capital punishment, right on down the line. The Democrats have the hammer, and they used it,” he said.

Former Rep. Bob Beauprez (R), who ran unsuccessfully for governor in 2006, said developments in Washington have also made Udall “a little more vulnerable” than he was just a few months ago. 

“The six-year itch is starting to take effect. The impact of the scandals is starting to take effect, the Obama team hasn’t had a really good five to six months. I think some of that is starting to show up in, maybe, Mark’s vulnerability,” he said.

Indeed, Udall’s favorability dropped somewhat from 50 percent in a Democratic poll in April to 45 percent in a June Quinnipiac poll.

But the prospect of a contested primary could spell trouble for Republicans if party members waste resources hammering each other rather than Udall. 

In addition to Baumgardner and Hill, state Rep. Amy Stephens is looking at a run.

Colorado Republicans say Buck, who ran a tight race against Bennet, may also run, but he is said to be considering a campaign for state attorney general as well.

Buck, observers say, might amass enough of a campaign war chest to persuade other contenders to drop out of the race. 

In his 2010 race, he raised about $5 million to challenge Bennet.

Beauprez himself is looking at running and said he expects to have a decision on whether he’ll enter the Senate or the gubernatorial race by Labor Day.

“Mark [Udall] is a very accomplished politician. It will be an extremely challenging, extremely expensive race, and you’ll need somebody who has been in the barrel before,” he said.

Beauprez touted his network of national and local donors as an advantage he might bring to a Senate race that’s likely to cost $15 million to $20 million, by his estimation.

Udall already has $3.4 million cash on hand for his reelection bid.

Dudley Brown, executive director of the anti-gun control group Rocky Mountain Gun Owners, said he expects bigger names than Baumgardner and Hill to jump into the GOP field.

“I believe there’s a candidate who’s going to clear the field pretty quickly, and I don’t suspect it will take long to find that out,” he said.

Beauprez acknowledged that the state GOP has some work to do to catch up with the Democratic machine in the swing state.

“I do know how effectively the Democrats play in Colorado. They’re quite good at it,” Beauprez said. “I think we have got to modernize our campaign strategy to compete with what has become a very effective Democratic campaign machine in Colorado as well as nationally.”