U.S. Rep. Trey Radel said Wednesday night he will take a leave of absence for an unspecified time and donate his salary.
"I have no excuse for what I have done. I have let down our country," he said at a news conference.
Radel spoke to reporters after returning home to southwest Florida, hours after he pleaded guilty to misdemeanor cocaine possession.
The 37-year-old first-term Republican from Florida said he will enter an inpatient drug treatment program to get treatment for substance abuse.
He hopes to set an example for those who struggle with addiction, CNN's Alina Machado reports.
The cocaine possession charge came after authorities said he bought a small amount of cocaine in a sting in the nation's capital last month
During the brief news conference, Radel said he "grew up with a mom who struggled with alcoholism."
"I don't want my son to struggle with that," he said.
The plea and sentence were part of a deal that Radel's attorney struck with federal prosecutors. He could have received a maximum sentence of 180 days imprisonment or a $1,000 fine, or both. Instead, he was placed on one year probation, and if it is "successfully completed," his guilty plea will be cleared from his record.