WASHINGTON — Florida Republican Rep. Henry “Trey” Radel pleaded guilty Wednesday to a misdemeanor charge of cocaine possession and was sentenced to a year’s probation.

“I’ve hit a bottom where I realize I need help,” Radel told District of Columbia Superior Court Judge Robert Tignor in acknowledging that he purchased 3.5 grams of cocaine from an undercover agent.

A Drug Enforcement Administration official said Radel bought cocaine in a Washington, D.C., neighborhood on Oct. 29. Later that night, federal authorities went to his apartment and informed him that he would be facing criminal charges. The charges were made public Tuesday, and Radel expressed regret in a statement.

The 37-year-old lawmaker said he struggles with alcoholism and will seek treatment and counseling. Radel made no mention of his political future but says he had made an “extremely irresponsible choice” and let down his family and his constituents.

“I want to come out of this stronger,” Radel said in court, later adding that he wants to “continue serving this country.”

The DEA official, who spoke on the condition of anonymity because he was not authorized to release details of the case in his own name, said Radel was identified to authorities as a cocaine buyer by his suspected dealer. The dealer had been arrested previously as part of a separate drug investigation led by a federal task force.

“In facing this charge, I realize the disappointment my family, friends and constituents must feel. Believe me, I am disappointed in myself, and I stand ready to face the consequences of my actions,” Radel said in a statement.

“However, this unfortunate event does have a positive side. It offers me an opportunity to seek treatment and counseling,” he added. “I know I have a problem and will do whatever is necessary to overcome it, hopefully setting an example for others struggling with this disease.”

The cocaine possession charge, a misdemeanor, carries a statutory maximum of six months in prison and a fine of $1,000. Radel appears to be the first sitting member of Congress charged with a drug offense since former Rep. Frederick Richmond, D-N.Y., was convicted in 1982 on charges of tax evasion and drug possession.

A spokesman for House Speaker John Boehner, R-Ohio, said the allegations are a matter for the courts.

“Beyond that, this is between Rep. Radel, his family and his constituents,” Boehner spokesman Michael Steel said.

Radel was elected in 2012 to represent Florida’s 19th Congressional District, which includes the Gulf Coast communities of Fort Myers and Naples. He was a radio host before becoming a congressman. He identifies himself on his Twitter profile as a “Hip Hop conservative” and “lover of #liberty,” and his Twitter account has remained active in the past few weeks, including on the day of the bust.

Among the bills he’s co-sponsored during his freshman term is legislation to amend the country’s mandatory minimum drug sentencing laws.

Florida Republican Party Chairman Lenny Curry said he was disappointed in Radel but glad that he was seeking help.