Colorado Sen. Michael Bennet may turn out to be the luckiest senator of 2016.  

He was supposed to be the only Democratic senator Republicans had a chance of knocking off this year.

But with the GOP primary next month, it doesn’t look like the party is much closer to making that happen than they were months ago, when they were still waiting for a candidate in Colorado who could knock off an incumbent — another Cory Gardner — to enter the race.

Nearly every candidate in the GOP’s crowded primary field has struggled to either get on the ballot or raise enough money to mount a viable campaign.

[Colorado GOP Squabbles Complicate Bennet Challenge]

The GOP’s internal struggles gave Bennet, the state’s senior senator who started the second fundraising quarter in April with $7.6 million in the bank, plenty of time to run positive spots touting his legislative accomplishments and reintroducing himself to voters.

The establishment pick

Former state Rep. Jon Keyser was widely regarded as the establishment pick in the June 28 GOP primary. He 
rolled onto the scene
in January as the “made-for-TV” candidate who told The Colorado Statesman
he had received $3 million in soft money commitments at the Republican Jewish Coalition’s presidential forum in Washington late last year.

[Republican Jon Keyser Enters Colorado Senate Race]

But Keyser has had a particularly tough time of late.

Last week, he refused to answer questions about his campaign submitting 10 forged signatures — including one of a dead person — to qualify for the ballot. An interview with the reporter who uncovered the forgery took a bizarre turn when Keyser asked the reporter if he had been “creeping around” his house.

When the reporter confirmed that he had knocked on Keyser’s door the day before, Keyser started talking about the size and might of his dog.

“He’s a great dog. He’s bigger than you are. He’s huge. He’s a big guy. Very protective,” Keyser told the reporter.

In a Tuesday night debate hosted by The Denver Post, Keyser tried to “clear the air” over the signatures. He blamed the incident on a single employee of a subcontractor that his campaign hired to gather signatures.

Pressed by the moderators about whether he bore any responsibility, Keyser instead blamed the media for having a liberal bias. 

The good news for Keyser is that, unlike some of his rivals, he successfully sued to make it onto the ballot. Candidates are required to collect 1,500 signatures from each of the state’s congressional districts to petition onto the ballot.

The rest of the pack

But with the forgery issue now raising new questions about Keyser, attention is turning to businessman Robert Blaha.

[Bennet Gets GOP Challenger After Iran Deal Vote]

He, too, had trouble getting on the ballot but was eventually allowed on. And he’s got money on his side. He had loaned his campaign $1 million by the beginning of the second quarter. His campaign has a second cable and broadcast TV ad hitting the airwaves within the week.

The ballot confusion in the GOP primary, combined with the presidential primary settling down, has resulted in increased media attention on the Colorado Republican field. That’s been good news for Blaha.

“All the sudden it has gone form, ‘Is there a Senate race in Colorado?’ to ‘Wow, there’s a lot to talk about here,'” Blaha said. 

Wealthy businessman and former Colorado State University athletic director Jack Graham has also put significant personal resources into his campaign and filed the requisite signatures to make it onto the ballot.

The rest of the field includes former El Paso County Commissioner Darryl Glenn, who qualified for the ballot at the state’s GOP convention last month, and former Aurora City Councilman Ryan Frazier, who is still waiting to hear whether his ballot signatures will earn him a spot. Glenn had only $11,000 in the bank at the end of the first quarter.

Ballot woes aren’t unique to Colorado, and they don’t necessarily foretell an unsuccessful campaign. In Indiana’s GOP primary, Rep. Todd Young stunned the establishment when he nearly failed to qualify for the ballot. He later defeated his primary opponent by 34 points.

But ballot struggles weren’t the first sign of trouble for Republicans in this race. A number of
high-profile Republican recruits
passed on challenging Bennet last year.

[GOP’s Preferred Candidate Passes on Colorado Senate Run]

Part of that may have to due with Bennet. He hasn’t alienated people in Colorado, said a Republican source with knowledge of the state.

A tough year

National Republicans maintain that Bennet’s approval ratings make him vulnerable. The National Republican Senatorial Committee is still attacking Bennet and hoping to put him on the defensive on national security. 

But challenging an incumbent in any year is tough, and that’s especially so with a crop of largely unknown candidates.

The GOP’s internal disarray — combined with the odds of Colorado going blue in a presidential year — prompted the Rothenberg & Gonzales Political Report/Roll Call to
switch the race’s rating
from lean Democrat to Democrat favored earlier this month.

[Republicans Struggle to Keep Colorado Senate Race in Play]

The standard GOP response to questions about recruiting struggles in Colorado over the past year has typically been
one name
: Gardner’s.

The then-4th District congressman entered the 2014 Senate race in March and 
cleared the field
. His late entrance gave hope to Republicans this year that there was still time for a consensus candidate to emerge.

But it’s now mid-May, and Republican chances of flipping Colorado’s second Senate seat look more daunting. 

“A swing state in a year of unknowns makes it a winnable race, but it’s a little bit harder race,” said the GOP source.

Contact Pathé at simonepathe@cqrollcall.com and follow her on Twitter @sfpathe.    

Get breaking news alerts and more from Roll Call on your iPhone or your Android.