Richard Grenell, whom Mitt Romney chose last month as his presidential campaign’s national security and foreign policy spokesman, stepped down from his post Tuesday, suggesting that the conservative backlash over his sexuality prevented him from being effective in his role.

In a statement provided to The Washington Post, Grenell, who is openly gay, said: “While I welcomed the challenge to confront President Obama’s foreign policy failures and weak leadership on the world stage, my ability to speak clearly and forcefully on the issues has been greatly diminished by the hyper-partisan discussion of personal issues that sometimes comes from a presidential campaign.” He added: “I want to thank Governor Romney for his belief in me and my abilities and his clear message to me that being openly gay was a non-issue for him and his team.”

Widely known in conservative circles, Grenell was named President George W. Bush’s spokesman to the United Nations in 2001, and served as communications director under four U.S. ambassadors to the United Nations, including John R. Bolton, who is among his strongest supporters.

Grenell was a volunteer consultant to the Romney team before he was officially brought aboard, but the hiring was controversial from the start.

Shortly after Romney announced that Grenell would join his team, the former spokesman for the U.S. mission to the United Nations was forced to remove entries from his Twitter account that some considered offensive. Grenell came under fire for a series of snarky tweets aimed at women, including Secretary of State Hillary Rodham Clinton; MSNBC talk show host Rachel Maddow; and Callista Gingrich, the wife of GOP presidential candidate Newt Gingrich.

Richard Grenell resigned from the Romney campaign on Tuesday, suggesting that the conservative backlash over his sexuality prevented him from being effective in his role. (STEPHEN HILGER/BLOOMBERG NEWS)

The tweets included posts about Clinton’s appearance, Gingrich’s hair and Maddow’s lack of jewelry, but Grenell was forced to address complaints that his comments were sexist even before he moved into his new role.

And some longtime reporters openly complained about Grenell’s confrontational style, which sometimes included calls to editors and freezing reporters out of stories. Among Romney’s biggest champions in the twitterverse, Grenell often used his Twitter account to call out reporters and to criticize U.N. Ambassador Susan Rice.

But it was social conservatives who balked most over the choice.

Matthew J. Franck, director of the William E. and Carol G. Simon Center on Religion and the Constitution at the Witherspoon Institute, called Grenell a “loose cannon” with a passion for the “gay agenda.”

“My problem is that by his own description he is an ardent activist for same-sex marriage who went to go work for a candidate who wants to defeat same-sex marriage. It doesn’t look good to the people that Romney needs support from to have an advocate for same-sex marriage in such a high-profile position,” Franck said. “The Romney campaign needs to be unequivocally opposed to same-sex marriage and to appear to be. The campaign has remedied a problem that was bound to get worse.”

While discussions of foreign policy have been front and center in the campaign for the White House, Grenell has been largely absent.

The Romney team maintains that it was Grenell’s decision to leave his post.

“We are disappointed that Ric decided to resign from the campaign for his own personal reasons,” campaign manager Matt Rhoades said in a statement. “We wanted him to stay because he had superior qualifications for the position he was hired to fill.”

Jennifer Rubin, who writes The Washington Post’s Right Turn blog, contributed to this report.