A top aide to Fred Thompson stepped down Monday.
WASHINGTON (CNN) - A top advisor to former Tennessee Sen. Fred Thompson announced Monday he was resigning his position with the Republican's presidential campaign, a day after news surfaced he pleaded guilty more than 20 years ago to drug charges.
"The focus of this campaign should be on Fred Thompson's positions on the issues and his outstanding leadership ability, not on mistakes I made some 24 years ago," Phillip Martin said in a statement issued by Thompson's campaign. "I deeply regret any embarrassment this has caused."
It was first reported Sunday in the Washington Post that Martin pleaded guilty in 1979 to selling 11 pounds marijuana and no contest in 1983 to cocaine trafficking charges.
Thompson said yesterday he was unaware of the man’s past, and but he wouldn’t “throw my friend under the bus.”
He did say he would talk to Martin, and acknowledged “I’m running for president, I’ve got to, you know, do the right thing.”
– CNN's Mary Snow contributed to this report