Richard Grenell, presumed Republican nominee Mitt Romney's first openly gay spokesperson, quit amid backlash by social conservatives after just two weeks on the job.

The Washington Post's Jennifer Rubin exclusively obtained the statement, in which Grenell hints that criticism over the hiring of an openly-gay aide prevented him from doing his job:

I have decided to resign from the Romney campaign as the Foreign Policy and National Security Spokesman. 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. 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.

The Romney campaign responded with its own statement: We are disappointed that Ric decided to resign from the campaign for his own personal reasons, said Matt Rhoades, according to the Post. We wanted him to stay because he had superior qualifications for the position he was hired to fill.

Grenell had been a loyal Republican for years and had an impressive resume in foreign policy, serving under four U.S. ambassadors to the UN during the presidency George W. Bush. His appointment has been seen as a milestone in GOP politics.

Still, some social conservatives claimed his support for same-sex marriage would be a conflict-of-interest when working for a Republican administration. Among the loudest critics of Grenell's hiring was Bryan Fischer of the American Family Association. On April 20, he tweeted Romney picks out & loud gay as a spokesman. If personnel is policy, his message to the pro-family community: drop dead.

Matthew J. Franck also criticized the Romney campaign for hiring an openly gay aide in the conservative-leaning National Review.

So here's a though experiment, Franck wrote. Suppose Barack Obama comes out -- as Grenell wishes he would -- in favor of same-sex marriage in his acceptance speech at the Democratic National Convention. How fast and how publicly will Richard Grenell decamp from Romney to Obama?

He had also been criticized for personally attacking Callista Gingrich, Michelle Obama, Rachel Maddow and other members of the media on Twitter. 

Bill Burton, a senior strategist and co-founder of the pro-Obama super PAC Priorities USA, blasted the GOP over the incident in a tweet.

This is the kind of bigoted, anti-gay extremists a Romney administration would find itself hostage to, he wrote, linking to the Washington Post story.