WASHINGTON — Opponents of Secretary of Defense nominee Chuck Hagel are fuming in the aftermath of sloppy work by their allies that has backfired and risks turning their cause into a joke.

The bumble: A thinly sourced claim that Hagel had taken money from a heretofore unheard of group called "Friends of Hamas," floated by the conservative website Breitbart.com, and sourced to Capitol Hill.

"This sort of thing drives me crazy because it undermines legitimate concerns about Sen. Hagel, his views and financial associations," said a Senate Republican aide involved with the anti-Hagel efforts. "In this business we deal in facts or the pursuit of facts and making up groups like the Friends of Hamas distracts us from legitimate questions as to what private foreign foundations and wealthy foreign individuals are contributing to the Atlantic Council or investing in Sen. Hagel's firms."

"We don't need to make things up about Sen. Hagel to sink his nomination because there's

already enough in his own record that should disqualify him," the aide said.

Other conservatives declined to speak on the record but described the attack as "idiotic" and as undermining the cause.

The shadowy group "Friends of Hamas," which Hagel was accused of receiving donations from, appears to have originated as a joke from a reporter to his source that the source then spread to others as a fact, according to an account by the reporter, Dan Friedman of the New York Daily News, on Wednesday.

The source is identified as a Capitol Hill Republican in the story, but in an email, Friedman refused to elaborate.

"As you note, I am trying to protect a source who kind of burned me," Friedman said. "But that's what I'm doing. I would like to help you, but I don't want this person to be outed, and I don't want to go beyond what the story says."

Friedman's joke became went viral when it appeared in a Breitbart News article as information coming from Senate sources. Opponents of Hagel, including former Gov. Mike Huckabee, started picking up on it and publicly citing it to demand that Hagel release more financial records.

But Friends of Hamas appears not to exist, as Slate's Dave Weigel wrote last week.

And nobody on the Hill is looking to take credit for the allegation. Indeed, spokespeople for Ted Cruz's, John McCain's, and Jim Inhofe's Senate offices, three of Hagel's chief opponents, specifically denied to BuzzFeed the rumor was spread by any of their staff.

Breitbart's Ben Shapiro, who authored the first Friends of Hamas report, stuck with his source on Wednesday and accused Friedman of lying.

"Our Senate source denies that Friedman is the source of this information," Shapiro wrote in a post that also referred to Friedman as a "hack." "'I have received this information from three separate sources, none of whom was Friedman,' the source said."

"I don't want to get into a debate with Ben," Friedman wrote in an email to BuzzFeed. "What I wrote is correct."