In a video message on Thursday, Farenthold acknowledged that there was an "unprofessional" environment in his office.
"I'd never served in public office before," he said. "I had no idea how to run a congressional office and as a result, I allowed a workplace culture to take root in my office that was too permissive and decidedly unprofessional."
He said "off-hand comments" and "off-color jokes" were "less than professional." He added that the "stress" of the job sometimes led to "angry outbursts" on his part.
"That was wrong," he said, adding that he is "profoundly sorry."
Farenthold’s decision to drop a re-election bid follows a report that he used $84,000 in taxpayer funds from a congressional account to settle a 2014 sexual harassment lawsuit by a former employee, and a report that he created a vulgar and hostile work environment.
The news also comes after the House Ethics Committee announced that it opened an investigation into Farenthold’s conduct.
Farenthold, 55, faced pressure to step down after the allegations and his use of the congressional account came to light. House Speaker Paul Ryan (R-Wis.) told reporters Thursday that he spoke with Farenthold and he thinks “he’s making the right decision to retire.”
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“There are new stories that are very disconcerting. Unacceptable behavior has been alleged in those stories and I think he’s made the right decision that he’s going to be leaving Congress,” Ryan said. “That reflects some of the conversations we had."
What are the allegations against Farenthold?
Politico reported earlier this month that Lauren Greene, Farenthold’s former communications director, sued him in 2014 over claims of gender discrimination, sexual harassment, and creating a hostile work environment.
Greene said in the lawsuit that another Farenthold staffer told her the lawmaker spoke of “sexual fantasies” and “wet dreams” about her. She alleged that after she objected to comments Farenthold and a male staffer had made to her, the lawmaker terminated her employment.
Farenthold denied the allegations, according to the report, but later paid $84,000 from a congressional account to settle the lawsuit.
CNN reported that a former senior aide to Farenthold told the House Ethics Committee that the lawmaker was “verbally abusive and sexually demeaning” to his staff.
Michael Rekola, who worked as Farenthold's communications director in 2015, told CNN that the congressman frequently made “sexually graphic jokes” and berated aides.
Rekola said that in July 2015, as he was preparing to leave town for his wedding, Farenthold made an inappropriate and graphic remark about his fiancée:
Farenthold, standing within earshot of other staffers in his Capitol Hill office, said to the groom-to-be: "Better have your fiancée blow you before she walks down the aisle — it will be the last time." He then proceeded to joke about whether Rekola's now-wife could wear white on her wedding day — a clear reference, Rekola said, to whether she had had premarital sex.
"I was disgusted and I left. I walked out," Rekola said, adding that he gave his two-weeks notice almost immediately after returning from his wedding.
Elizabeth Peace, who also worked in Farenthold's communications efforts, told CNN she heard Farenthold make the remark as Rekola described.
"Every staffer in that area heard it," Peace said. "It was the most shocking thing I'd heard him say at that point."
Both staffers also said Farenthold regularly called his aides "f***tards."
Rekola added that minor mistakes — such as a failure to respond to emails fast enough — could lead to outbursts from Farenthold.
"Every time he didn't like something, he would call me a f***tard or idiot. He would slam his fist down in rage and explode in anger," Rekola said. "He was flying off the handle on every little thing. I couldn't find a way to control it.”
In a statement to CNN, Farenthold denied abusing his staff or making the remark about oral sex. He did, however, admit to calling his staff "f***tards," but said it was "in jest, not in anger."
"In hindsight, I admit it wasn't appropriate," Farenthold said.
Farenthold represents a south Texas seat, and had already attracted primary challengers before his decision to not seek re-election.