In a potentially bad sign for Rep. Doug Lamborn’s (R-Colo.) re-election hopes, the National Association of Home Builders has endorsed one of his two challengers in the Aug. 12 GOP primary.

The NAHB is backing former House aide and one-time Colorado Springs Chamber of Commerce executive Jeff Crank (R), who narrowly lost to Lamborn in the 2006 GOP primary, Crank’s campaign revealed this week. Retired Air Force officer Bentley Rayburn (R), who also sought the Colorado Springs-area 5th district in 2006, is running again this year.

Lamborn has struggled to raise money since winning an easy general election race in 2006 — the 5th district is overwhelmingly conservative territory — and one Republican strategist called this “a really bad sign because it is just further proof that Lamborn has failed to connect with K Street, and his fundraising numbers are further proof of it.”

Lamborn closed the first quarter of this year with nearly $180,000 on hand and almost $60,000 in campaign debt.

Lamborn’s campaign referred a request for comment to his Congressional office, which did not have an immediate comment Tuesday.

However, another Republican operative, this one a veteran Washington, D.C., fundraiser, said the NAHB’s endorsement of Crank could have more to do with state politics in Colorado than anything else, although this operative still referred to the organization going against an incumbent in a primary as “a little bit of a big deal.”