Florida’s Rep. Trey Radel will resign from Congress on Monday evening, a decision he said stems from his inability to serve effectively.

“Unfortunately, some of my struggles had serious consequences. While I have dealt with those issues on a personal level, it is my belief that professionally I cannot fully and effectively serve as a United States Representative to the place I love and call home, Southwest Florida,” he wrote in his letter of resignation to House Speaker John Boehner.

His announcement came less than one month after returning to work from drug rehabilitation on Jan. 7. Radel reentered his position in Congress after he took a leave of absence last November for pleading guilty to cocaine possession. Several leaders called on him to resign, and a super PAC raised $1 million to challenge him from running for office a second time.

Police arrested the first-term Republican congressman last October in Washington, D.C., for buying 3.5 grams of cocaine from an undercover agent. After his arrest, he entered drug rehabilitation, took a leave of absence, and said he would donate his salary to charity while in treatment.

The 37-year-old, who was a regular cocaine user and buyer at the time of his arrest, attended rehabilitation in Florida after a judge sentenced him to a year of probation.

“Regardless of some personal struggles in 2013, this year has already been tremendously positive as I focus on my health, family and faith,” he wrote. He sent a similar letter to Florida Gov. Rick Scott.