Republican congressman Trent Franks of Arizona said Thursday he is resigning next month after revealing that he discussed surrogacy with two female staffers.

The eight-term lawmaker, a staunch conservative and fierce opponent of abortion, said in a statement that he never physically intimidated, coerced or attempted to have any sexual contact with any member of his congressional staff.

Instead, he says, the dispute resulted from a discussion of surrogacy. Franks and his wife have three-year-old twins who were conceived through surrogacy.

Franks says he had become familiar with the surrogacy process in recent years, and "became insensitive as to how the discussion of such an intensely personal topic might affect others."

He said he regrets that his "discussion of this option and process in the workplace" with two female staffers made them feel uncomfortable.

In a statement, Speaker Paul Ryan, a Republican from Wisconsin, said that when he learned of the allegations, which he considered "serious and requiring action," he told the lawmaker he should resign.

Franks said he would step down effective Jan. 31, 2018.

Staunch social conservative

In a one-page statement late Thursday, the House ethics panel said its members were examining whether Franks "engaged in conduct that constitutes sexual harassment and/or retaliation for opposing sexual harassment." The statement provided no further detail and noted that while it was establishing an ethics subcommittee, that didn't mean that any violations of law or House rules had occurred.

Franks was seen being comforted in the House chamber by several other Republicans. They included Texas representative Louie Gohmert, Alabama's Robert Aderholt and fellow Arizonan Andy Biggs.

Asked for comment as he left the floor, Franks said, "I'll let the statement speak for itself."

Franks has been a member of the far-right House Freedom Caucus. He's a staunch social conservative who sponsored House-passed legislation to make it a crime for any person to perform an abortion if the age of the fetus is 20 weeks or more.

Earlier Thursday, Sen. Al Franken, a Democrat from Minnesota, announced his resignation after facing allegations of sexual harassment by at least eight women. Franken said some of those accusations were false and said he remembered others differently than his accusers did. He said he'd depart in a few weeks.

On Tuesday, representative John Conyers, a Democrat from Michigan, resigned effective immediately. He also faced accusations from women of improper sexual behaviour that he's contesting.

Controversial rape comment

Franks drew a sharp response from Democrats during a 2013 House committee debate when he said "the incidence of rape resulting in pregnancy are very low." He sought to clarify the comment, saying later-term abortions linked to pregnancies caused by rape are infrequent.

He's a strong backer of President Donald Trump and has embraced some of his stances on social issues. Franks has harshly criticized some NFL players for not standing during the national anthem, calling them "arrogant and overpaid Lilliputians who dishonour America."

Franks represents a district encompassing suburbs north and west of Phoenix. He serves on the House Judiciary and Armed Services committees.

Before winning election to Congress, he served in the Arizona legislature and founded the Arizona Family Research Institute, an organization associated with Dr. James Dobson's Focus on the Family, which describes itself as a global Christian ministry that provides "help and resources for couples to build healthy marriages that reflect God's design, and for parents to raise their children according to morals and values grounded in biblical principle."