From CBS News' Scott Conroy:

COLUMBIA, S.C. -- There was an ice storm in South Carolina this morning, but it was even colder inside a Staples store where a Mitt Romney press conference suddenly went sour.

Romney was in the middle of answering a routine question when he said something that caused Associated Press reporter Glen Johnson to lose his temper.

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

“That’s not true, governor!” Johnson suddenly interjected. “That is not true. Ron Kaufman is a lobbyist.”

Kaufman is a well-known lobbyist, former adviser to President H.W. Bush and Romney campaign adviser who is often seen by the governor’s side while on the road.

Click on the video below to watch as the exchange between Johnson and Romney as it grew increasingly hostile.