Republican Congressman Trent Franks of Glendale is resigning after House Speaker Paul Ryan told him to step down, based on "credible claims of misconduct" by two former female staffers.

Franks, a social conservative who has served eight terms in Congress, announced Thursday he's resigning as of Jan. 31, rather than face a House Ethics Committee investigation:

"In the midst of this current cultural and media climate, I am deeply convinced I would be unable to complete a fair House Ethics investigation before distorted and sensationalized versions of this story would put me, my family, my staff, and my noble colleagues in the House of Representatives through hyperbolized public excoriation. Rather than allow a sensationalized trial by media damage those things I love most, this morning I notified House leadership that I will be leaving Congress as of Jan. 31, 2018."

Franks said in a prepared statement that he recently learned the ethics committee was investigating his discussions of having a surrogate baby with the two former staffers. The staffers were uncomfortable with the conversation, he said.

"Due to my familiarity and experience with the process of surrogacy, I clearly became insensitive as to how the discussion of such an intensely personal topic might affect others," Franks said.

"I deeply regret that my discussion of this option and process in the workplace caused distress."

In a prepared statement, Ryan said he had presented "credible claims of misconduct" to Franks last week and told him he should resign.

Ryan said Franks did not deny the allegations.

Ryan referred the allegations to the House Ethics Committee last Friday.

"The speaker takes seriously his obligation to ensure a safe workplace in the House," the statement said.

Franks, an anti-abortion, family values congressman, has been dogged by rumors of inappropriate behavior for several years, according to several political operatives in Arizona.

Franks had planned to run for the U.S. Senate in 2012, going as far as booking a Phoenix hotel meeting room for the announcement. But it was abruptly canceled just hours before the scheduled start.

The 60-year-old Franks represents a safely Republican West Valley district. He is married and has two children.

Franks is one of the 50 richest members of Congress, with a net worth of $9.85 million, largely from an oil business, according to Roll Call.

Under Arizona law, Franks' constituents in the Eighth Congressional District will go to the polls four times next year to elect his successor.

The governor will have to call a special primary election within 80 to 90 days after Franks' resignation Jan. 31, with a special general election to fill the seat within 50 to 60 days after the primary.

The winner would run again in the regularly scheduled August primary and November general election.

Republican State Sen. Debbie Lesko of Peoria told 12 News Thursday evening she was interested in running for the Franks seat.

Earlier in the day, Democratic Minnesota Sen. Al Franken announced he would resign in the coming weeks after several women accused him of groping and sexually harassing them.