Rocky Mountain State Republicans continue to struggle in their search for a challenger for Sen. Mark Udall, D-Colo., thanks to the fractious nature of the state’s party.

The field of potential candidates reflects a shallow GOP bench in a race that should pique the interest of any ambitious Colorado Republican. Since the start of the cycle, the field of potential candidates has evolved into a mix of young talent, old names, and middle-rank state legislators.

“There are a lot of viable candidates who wouldn’t scare the hell out of suburban women …who could actually win a general,” said lobbyist Mike Beasley, a former staffer to former Gov. Bill Owens, a Republican. “But a lot of them wouldn’t want to suffer through … what continues to be these weird, stranger and stranger primaries.”

Weld County District Attorney Ken Buck, the party’s failed 2010 nominee for Senate, is the latest Republican to express interest, via the Denver Post. Buck made a handful of gaffes in 2010, and many Republicans blame him for blowing a contested race against Democratic Sen. Michael Bennet.

That report about Buck was the first time operatives at the National Republican Senatorial Committee say they heard the news, according to an NRSC source.

“We don’t believe that this is the right time for politics in light of Senator Udall’s family situation,” replied an NRSC operative in a Wednesday email requesting comment, referring to Udall’s missing brother.

Besides Buck, other Republican contenders include:

• State Rep. Amy Stephens: If she runs, her base in a GOP primary will likely come from social conservatives. A former Focus on the Family employee, her speaker site biography details her anti-abortion views.
• Former Rep. Bob Beauprez: His name surfaced in January and Republicans continue to point to him as a contender. He was the GOP’s unsuccessful gubernatorial nominee in 2006.
• State Sen. Owen Hill: He expressed interest to the local Fox affiliate in running. Even Democrats will concede that his legislative career has had an impressive start. But unprompted, operatives from both parties note the brevity of it — he was sworn into the state Senate in January.
• State Sen. Scott Renfroe: Tea party activist and radio host Ken Clark named Renfroe as an ideal candidate, but Renfroe has not made any formal announcements.

As for Buck, it’s unclear whether he would have the inside track to the nomination. There is no kingmaker in Colorado GOP politics to anoint him or any other candidate, and the Colorado Republican Party harbors deep fractures on social issues and immigration — especially with tea party activists.

“It all comes down to what the grass-roots decides,” Colorado Republican Party spokesman Owen Loftus said.

The Rothenberg Political Report/Roll Call rates this race as Safe Democrat.