Mario Diaz doesn’t mince words.

The Phoenix-based lobbyist, who is close with Homeland Security Secretary Janet Napolitano, recently demonstrated unusual candor in pitching his firm to potential federal clients.

“In the government relations world, even in Arizona, it’s not what you know, it’s who you know,” he wrote in a recent letter introducing himself to established K Streeters.

It seems Diaz is willing to put in writing what most lobbyists fear to say.

“We all know in this town that who you know is important, but we would never say it. Or put it in writing,” one lobby shop executive said.

Diaz notes that he has a long history of working for Napolitano, going back to her days as Arizona’s U.S. attorney, attorney general and governor. But he doesn’t stop with her.

“My firm, Mario E Diaz & Associates, is a government and public relations firm with excellent working relationships with DHS personnel, specifically with Noah Kroloff, Chief of Staff for Secretary Napolitano, and Art Macias, Chief of Staff” for the Transportation Security Administration, Diaz wrote in the letter. “Should you or your client(s) have a need to reach out to the Department of Homeland Security, my firm could be a great asset.”

In an interview, Diaz said the letter is part of his firm’s marketing campaign.

The part about “it’s who you know,” he said, is just drawing on a common phrase. “It is not meant to imply that you hire us to have access,” Diaz said while he was in town last week as a guest of Speaker Nancy Pelosi (D-Calif.) during Mexico President Felipe Calderon’s address to Congress. “We know folks. We can be helpful. If the concern is the language, I’ll take a look at it.

“If it’s perceived to be too heavy-handed, then it’s not a good way to introduce myself to the D.C. crowd,” he added. “We have a very ethical firm. We’re hardworking people, and we’re reaching out to companies to say we exist.”

Ken Gross, a lobbying ethics expert at Skadden, Arps, Slate, Meagher & Flom, said there’s nothing in the letter that would violate any lobbying laws. “I don’t know of any statutory line that such an advertisement would cross, but it is not something you typically see laid out in this fashion.”

And veteran lobbyists agree the approach is unusually blunt.

“I would say where are his credentials for homeland security?” said one lobbyist, who would only speak on condition of anonymity. “If he’s saying it’s only ‘who you know,’ then I would be a little reluctant to work with him.”

Another lobbyist whose firm frequently works with Homeland Security clients said getting results for clients takes a lot more than just knowing key officials.

“Engaging DHS requires a lot of patience and a lot of connectivity to the operating agencies, as well as trying to influence DHS headquarters and their political appointees,” said Monument Policy Group’s Stewart Verdery, who served as assistant secretary for policy and planning at DHS during the George W. Bush administration.

DHS spokesman Matt Chandler said Diaz has not had any official meetings with Napolitano. He added, “Mr. Kroloff and Mr. Macias have known Mr. Diaz since they worked together in Arizona state government, but neither Kroloff nor Macias have neither met nor seen Mr. Diaz in any official capacity since they moved to D.C. to join the administration.”

Diaz noted that he is not currently a registered federal lobbyist, though he was briefly registered last year to represent the Operator’s Choice for Tactical Innovation, which paid him about $10,000, according to lobbying disclosures filed with Congress, and Touchstone Consulting Group, which paid him less than $10,000 for work last year.

In his letter, Diaz mentioned a client of “particular note,” defense contractor Lockheed Martin. In the interview, Diaz said he is not lobbying for Lockheed but is a special issues consultant.

“As a person from Arizona, away from the Beltway, I sure would like to get in this world,” said Diaz, who according to federal election data compiled by the Center for Responsive Politics has contributed $50,000 in this election cycle. He has donated to Members such as Arizona Democratic Reps. Gabrielle Giffords and Raúl Grijalva as well as House Majority Leader Steny Hoyer (D-Md.) and Massachusetts Sen. John Kerry (D). And he has given $30,000 to the Democratic Congressional Campaign Committee.

Another lobbyist who is familiar with the Homeland Security Department said that Napolitano’s tight network of Arizonans at the department makes Diaz’s pitch, although unusual, somewhat understandable.

“Napolitano did bring a cadre of people from Arizona to work directly for her as well as places like Customs and TSA,” the lobbyist said. “It’s an unusual amount of people coming in that the typical D.C. crowd didn’t know. I can understand why this fellow thinks this is a marketable set of relationships.”

And lobbyists say they, too, struggle with trying to lay out their ties to government officials in order to generate new business.

“You’re constantly debating how specific to get, how much detail you want to give,” one K Streeter explained. “I might say, ‘I know the following 32 people really well,’ but if that were to get out in writing, those 32 people aren’t going to be happy.”