Former representative Tom Tancredo (R-Colo.) blamed outside spending for his loss. (Shannon Stapleton/Reuters)

Though it ostensibly stays neutral in primary elections, the Republican Governors Association appears to have played favorites in at least one contest this year, apparently financing outside spending against a well-known fellow Republican.

The money — a little more than $150,000 — went to finance radio advertisements against former representative Tom Tancredo (R), who was making his second bid for governor.

Tancredo’s history as an immigration hardliner, and controversial comments that have infuriated Hispanic activists, made Republicans nervous in a state where Hispanics make up a growing portion of the electorate. National Republicans privately favored former representative Bob Beauprez (R), who ended up winning the June primary.

And the RGA appears to have put its money where its mouth was. In late June, the RGA contributed $175,000 to the Republican Attorneys General Association, a new outside group that spun off from a partner organization this year. A few days earlier, the RAGA contributed $155,000 to the Campaign for Jobs and Opportunity, a Massachusetts-based super PAC.

Citizens for Responsibility and Ethics in Washington, the campaign finance watchdog group, first reported the moving money this week.

A state-level affiliate of that super PAC began running radio advertisements accusing Tancredo of being a part of the problem in Washington, dubbing him a “big-spending Republican.” On its disclosure reports, the Colorado Campaign for Jobs and Opportunity listed contributions from its national affiliate.

Another outside group, dubbed Republicans Who Want to Win, received $75,000 in contributions from the Campaign for Jobs and Opportunity just before running its own advertising against Tancredo. Those advertisements ran in El Paso and Mesa counties, two Republican strongholds.

The late advertising appeared to have an impact: Beauprez beat Tancredo by less than four percentage points, or about 14,000 votes. Tancredoblamed the late spending for arresting his momentum.

Other Republicans were eager to keep Tancredo off November’s ballot as well. Rep. Cory Gardner (R), running against Sen. Mark Udall (D) in what has become a surprisingly close contest, worried privately that running with Tancredo at the top of the GOP ticket could have down-ballot impacts. But publicly, both Gardner and the RGA stayed silent.

Beauprez is now running close to Gov. John Hickenlooper (D), according to public polls. Two surveys conducted earlier this month showed the two running neck and neck; a Quinnipiac poll showed Beauprez leading by a single point, while an NBC News/Marist poll showed Hickenlooper up six.

“The race is about John Hickenlooper and his leadership failures as governor. Democrats are desperate and will try anything to take the focus off his plummeting job approval numbers,” Jon Thompson, an RGA spokesman, said in an e-mail. The RGA wouldn’t comment on the mystery money.