Interesting give-and-take with a reporter and Mitt Romney:

Mitt Romney scolded a veteran campaign reporter in South Carolina today after being challenged on claims about lobbyists’ involvement in the campaign.

Holding a news conference in front of the pen rack of a Columbia Staples store, Romney wanted to tout his “strategy for a stronger economy.”

Answering what reporters later called a routine question, Romney took a veiled shot at Sen. John McCain (R-Ariz.), who has jumped to a lead in Palmetto State polls.

“I don’t have lobbyists running my campaign,” Romney said. “I don’t have lobbyists that are tied to my — ”

Glen Johnson, an Associated Press reporter who was sitting on the floor as he typed on his laptop computer, interrupted to point out that Ron Kaufman, one of Romney’s top advisers, is a lobbyist.

“That’s not true, governor!” Johnson interjected, according to CBS News’ Scott Conroy, who was there. “That is not true. Ron Kaufman is a lobbyist.”

CBS has posted the video.

“Did you hear what I said — did you hear what I said, Glen?” Romney replied. “I said, ‘I don’t have lobbyists running my campaign,’ and he’s not running my campaign. He’s an adviser. And the person who runs my campaign is [campaign manager] Beth Myers, and I have a whole staff of deputy campaign managers.”

I’ve watched the video and I don’t think Romney “scolded” the reporter. Nor was he “angry” as some media outlets have labeled the exchange. That said, Johnson was well within his rights to press Romney on the issue, despite the objections of Romney’s press officer:

After the two separated, traveling press secretary Eric Fehrnstrom told Johnson he was “out of line.”

“Save your opinions and act professional,” Fehrnstrom added. “Don’t be argumentative with the candidate.”

Keeping candidates honest by pointing out facts and asking good questions shouldn’t be dismissed as “argumentative.” Just make sure you’re keeping candidates from both political parties honest.