WASHINGTON (WASHINGTON POST) - Representative Joe Barton of Texas, one of the longest-serving Republicans in the House, announced on Thursday (Nov 30) that he will not seek another term representing his suburban Dallas-Fort Worth district.

The announcement came after news reports revealing that Barton had carried on multiple extramarital relationships before his 2015 divorce. A lewd photo he sent to one of those women circulated online last week, prompting Barton to apologise.

One woman who spoke to The Washington Post on the condition of anonymity last week described a five-year relationship with Barton that began with an innocent Facebook message from the congressman that eventually led to explicit phone calls, text messages, photos and videos, as well as a pair of meetings.

Both Barton and the woman said the interactions were consensual, but the woman said she felt deceived and betrayed after she learned about other women Barton was having similar relationships with.

Barton confirmed his retirement, which was first reported by the Dallas Morning News, in a statement issued Thursday.

"I am very proud of my public record and the many accomplishments of my office," he said. "It has been a tremendous honour to represent the 6th District of Texas for over three decades, but now it is time to step aside and let there be a new voice."

Barton told the Dallas Morning News that he believes he could still win re-election.

"But it would be a nasty campaign, a difficult campaign for my family," he told the paper.

He faced increasing pressure from local Republican power brokers, and a GOP challenger filed papers to run against him on Wednesday.

The woman who spoke to The Post last week shared a recording of a 2015 phone call where Barton confronted her over her communications with other women he had propositioned.

In that context, Barton mentioned the Capitol Police - a comment the woman interpreted as an attempt to intimidate her.

"I want your word that this ends," he said, according to the recording. "I will be completely straight with you. I am ready if I have to, I don't want to, but I should take all this crap to the Capitol Hill Police and have them launch an investigation. And if I do that, that hurts me potentially big time."

"Why would you even say that to me?" the woman responded. "The Capitol Hill police? And what would you tell them, sir?"

Said Barton: "I would tell them that I had a three-year undercover relationship with you over the Internet that was heavily sexual and that I had met you twice while married and had sex with you on two different occasions and that I exchanged inappropriate photographs and videos with you that I wouldn't like to be seen made public, that you still apparently had all of those and were in position to use them in a way that would negatively affect my career. That's the truth."

Barton called the recording "evidence" of a potential crime, citing a Texas "revenge porn" statute, and said the Capitol Police were now investigating.

The woman denies any wrongdoing, including threatening Barton or posting the lewd photo publicly, and the Capitol Police have not commented on whether they intend to investigate.

Another woman, Kelly Canon, told the Fort Worth Star-Telegram in a story published on Wednesday that Barton had sent her inappropriate, sexually suggestive messages on Facebook in 2012 and 2013.

"Men are men... and u r definitely a sexy woman," he wrote to Canon, who is active in Republican politics in Arlington, Texas.

Texas's sixth Congressional District stretches from the suburbs south of Dallas and Fort Worth into rural areas south-east of the metroplex. The district has a nine-point Republican lean according to the non-partisan Cook Political Report, and supported Donald Trump by 12 points over Democratic nominee Hillary Clinton in last year's presidential election.

Barton was first elected to the House in 1984, making him fifth in overall seniority among Republicans. He is a former chairman of the House Energy and Commerce Committee who is known on Capitol Hill as a fierce advocate for the oil and gas industry and a foe of environmentalists. He serves as vice-chairman of that panel.