DENVER – Republicans hope to shake up the sleepy Colorado U.S. Senate race by injecting money into making incumbent Democrat Michael Bennet answer for the Iran nuclear deal.

The right-leaning Illinois-based Restoration PAC spent about $800,000 in July on statewide TV and digital advertising in the hopes of convincing voters that Republican challenger Darryl Glenn is a “political outsider” capable of being elected. They’re attacking Bennet to convey the message.

Glenn has been ignored by many of the usual Republican allies, and he has fought for attention from the national Republican Party, struggling to earn big-money contributions.

On Wednesday, Bennet’s campaign announced it had the support of more than 100 business leaders, including a handful of prominent Republicans, further highlighting Glenn’s struggles.

Recent polling has Glenn down by double digits.

But in the post-Labor Day build-up to the November election, some Republicans believe they can shift the race, or at the very least, show that Bennet has some opposition.

Restoration PAC hired a Denver-based GOP consulting firm, Clear Creek Strategies, to help with the effort to oppose Bennet. The focus will be on foreign policy issues, especially the Iran nuclear deal, which Bennet supported last year.

“The world is exponentially less safe now than when Senator Bennet last was elected, and he is a part of the reason,” said Doug Truax, executive director of Restoration PAC. “Every Coloradan is less safe today because of Senator Bennet’s vote to both empower Iran’s nuclear ambitions and to enhance Iran’s capacity to carry out terrorist attacks across the globe.”

The issue has followed Bennet, especially recently, as the Obama administration is criticized for handing $400 million to Iran, a payment critics say was tied to the release of four American hostages. Republicans frame the payment as “ransom.”

The Obama administration this week acknowledged two more cash payments totaling $1.3 billion, after delivering the $400 million by plane in January.

The administration announced in January that it would pay Iran $1.7 billion to settle claims dating to the incomplete sale of military weapons before the Iranian Revolution in 1979. But officials did not say how or when those payments would be made.

Democrats maintain that the cash payments are necessary to honor the nuclear deal, especially as sanctions have cut Iran out of the international banking system.

The goal of the compromise is to restrict Iran’s nuclear activities. The International Atomic Energy Agency, which reports to the United Nations, said Iran is limiting its stockpiles of substances that could be used to make atomic weapons, according to a report cited by Reuters.

But in Colorado, the politics of the deal swirl. U.S. Sen. Cory Gardner, a Republican, introduced legislation this week that would prohibit the United States from making “ransom” payments to any country. It also would prohibit the Treasury from making payments to Iran until Iran returns the $400 million and compensates American victims of Iranian terrorism.

The Colorado Republican Party quickly attempted to force Bennet’s hand by demanding that he support Gardner’s bill. Bennet has so far not commented on the legislation.

Democrats appeared unmoved Wednesday when Restoration PAC announced its presence in Colorado. A spokesman for the Bennet campaign turned the attack on Glenn.

“Darryl Glenn’s obstructionist agenda is out of touch with mainstream Coloradans and isn’t resonating with voters – maybe that’s why Glenn is ... leaving shady Super PACs to run his campaign instead,” said Bennet spokesman Andrew Zucker.

When The Durango Herald told a spokesman for the Colorado Democratic Party that a new PAC was “attempting” to shake up the U.S. Senate race, Chris Meagher responded only, “The key word in your question is ‘attempting.’”

Glenn on Thursday said of Bennet, “​With every month that​ goes by since the passage of the Iran nuclear deal, it becomes clear just how bad a deal it​ was for America, clear to everyone except Michael Bennet.”

Bennet’s campaign fired back with a website, MeetDarrylGlenn.com, that paints Glenn as a “partisan obstructionist wrong for Colorado.”

“The more voters learn about Darryl Glenn’s partisan obstructionism and backwards policy agenda, the clearer it is that he is out of touch and wrong for Colorado,” said Bennet campaign spokeswoman Alyssa Roberts. “Glenn says the problem with Washington is that Republicans have been too bipartisan. ... The choice could not be clearer.”

pmarcus@durangoherald.com