"...there is some "there" there"
Something in this doesn't seem right to me. Campaign donations are very difficult to keep track of. Assuming, perhaps Lamborn did wind up with 'dirty' money, but did he deliberately and knowingly accept that money?
The Bartha's letter might just as easily been mistaken or their charges exaggerated. If they have solid proof, then they need not fear their adversary. But in publishing that charge, they had to know there would be a reaction.
Maybe Lamborn's a jerk, but his jealousy over his reputation could not be unexpected. Is there anything in his history that might suggest his threats meant more a libel suit?
Sorry to be the devils advocate, but the Bartha's donned journalists' hats, and assumed that responsibility. It's unseemly for them to cry wolf over an angry verbal rebuttal.
The Lamborn folks kept track of the donation with enough accuracy to later allegedly return it.
All the Barthas did, was to write a letter to the editor. In response, they apparently got Lamborn being way over the top. A Congressman should expect folks to write things like that in the paper -- and he shouldn't respond as Lamborn is said to have done.