Mike Enzi, the popular, 69-year-old conservative U.S. Senator from Wyoming is prepping for the fight of his life.

Until last July, the soft-spoken, three-term legislator—who eschews interviews and remains one of D.C.’s most private denizens—did not anticipate a challenge for his GOP seat in 2014. But last summer, he received a sudden shock when feisty Liz Cheney, the 46-year-old, ultra-conservative daughter of former Vice President Dick Cheney, burst on the scene.

In her web announcement—made just 30 minutes after Enzi announced his candidacy—she took a swipe at Enzi’s age, proclaiming it was time for a “new generation of leaders to step up,” thereby rattling the Republican party, which hoped to avoid any primary conflict.

Many in the GOP establishment considered Cheney’s action extremely bad form and quickly rallied behind Enzi. Even flame-thrower Ann Coulter has weighed in. “Why should we be having a rancorous primary against a good Republican senator other than for Liz Cheney’s ego?” Coulter said during a televised interview.

The contretemps has quickly escalated into a battle royale. Dubbed “Chenzi” by the Casper Star-Tribune, the contentious race will prove to be the most expensive in the history of Wyoming politics. On Tuesday, to enhance her coffers, Cheney called John McCain a “liberal republican,” a brazen effort to attract the fringe of the GOP party—and their money.

Initially, the congenial Enzi seemed to be blindsided by the Cheneys. The former vice president was a longtime Enzi supporter and a fishing buddy. “I thought we were friends,” he told The Daily Beast during an interview in his office crammed with cowboy memorabilia late last week.

“I was surprised,” he said, “partly because I’d heard from people that [Dick Cheney] was calling and asking if Enzi didn’t run would you put somebody in her campaign…that’s where I got the impression that if I ran she wasn’t going to run. But everybody has the right to run; they just have to earn it.”

Liz moved to Wyoming in 2012 after years of living in Virginia. She bought an expensive and expansive home near Jackson Hole, where her parents also have a house, and became a regular on the rubber-chicken circuit. Her ambition and sense of entitlement apparently flow from her father’s decade of service as the congressman from Wyoming starting in 1979.

Enzi, on the other hand, grew up in Thermopolis, Wyoming, where he received the Distinguished Eagle Scout Award. He went on to earn a degree in accounting from George Washington University. He met and married fellow student Diana Buckley while getting an MBA from the University of Denver. In 1969, he returned to Wyoming to manage and expand his father’s shoe business, NZ Shoes, in Gillette. (He remains an expert fitter.) He said the job taught him the value of listening and compromise.

“You’ve got to listen to what the customer says and then you’ve got to see how what they want matches up with you inventory. It’s not always an exact match,” he said. “It works that way with legislation too. There are a whole bunch of bills and inventory here and they won’t always be an exact fit but you try and get the best fit that you possibly can.”

His civility and forthright manner caught the attention of Wyoming legislator and future U.S. Senator Alan Simpson, who launched Enzi’s political career after hearing him speak at a Jaycee dinner. “He gave a hell of a talk and I told him ‘I don’t care what party you are you should run for politics,’” said Simpson. “I urged him to run for mayor.”

Enzi served two terms as Gillette mayor, during which a boom in coal and natural gas turned Wyoming the nation’s energy capital. He went on to the Wyoming legislature and, when Simpson retired, won Simpson’s seat in the U.S. Senate in 1997.

Since then he been a quiet but extremely effective advocate for his approximately half million constituents. He’s considered the eighth-most conservative member of the Senate (“That’s my worst rating. I used to be no. three,” he said), yet he’s known for his ability to cooperate and work with Democrats—traits for which the Tea Party and Liz Cheney are now ferociously attacking him. Enzi joined the late Senator Ted Kennedy in passing bills on healthcare and number of other thorny issues. The secret, he said, is,” what we left out of the bills.”

To maintain cross-party civility, he adheres to a strict 80-percent rule. “There are 80 percent of the issues we can talk civilly about and find common ground,” he said. The other 20 percent he believes are best ignored.

Recently Simpson had a major dust up with Liz Cheney’s mother Lynne, who could not understand why he was not supporting her daughter. In a phone call from Cody, Wyoming, he told The Daily Beast that during a conversation at a charity event she told him to “shut up,” and then denied it, which infuriated the former senator. “I won’t be called a liar,” said Simpson, who has always backed Enzi and will continue to do so, even though he is very fond of Liz. “He’s very cool and knows all the issues. Liz does not.” But, he added, “Anyone with unlimited resources, handlers, advisors with 30-second responses has a shot to win.”

Neither side has been a slouch in fundraising. As of last week, Liz Cheney raised more than $1 million since her announcement. Enzi has raised $847,646 during same timeframe. Cheney has been trolling for big bucks in Washington, D.C. and New York, while Enzi’s donations are predominantly from within the state. Even when he was stuck in D.C. during the government shutdown—which he voted against terminating—Enzi sent fundraising letters home, which pulled in significant sums.

His goal, he said: “I want to have enough money to be credible.” But he said he’s unsure how many millions that will take. Enter, Bill Cubin, a CPA from Casper, who has established “Wyoming’s Own,” a super PAC supporting Enzi (the name of which is a clear jab at Cheney’s recent residency). “I think you’ll be surprised how easily he will win. In private polling his approval rating is in the 70s and 80s,” says Cubin. Cheney “offers nothing to Wyoming that we don’t already have.”

In his last two general elections Enzi has won with 70 percent of the vote. But Dick Cheney remains popular throughout the state, and some Republicans have called it a 50-50 race.

Wary of assaults from the far right he treks home every weekend, crisscrossing his sparsely-populated state, going door-to-door shoring up his conservative credentials. He has been pushing his seniority, his seat on the coveted Finance Committee and the support of his congressional colleagues.

“I’m going to do everything possible to convince the voters of Wyoming that they need to hire me again. You know, Wyoming is about the only state with a code of ethics and number nine of [its] code is: ‘Some things are not for sale’.”