Richard Grenell, the openly gay spokesman recently hired to sharpen the foreign policy message of Mitt Romney’s presidential campaign, resigned Tuesday in the wake of a full-court press by anti-gay conservatives.

Several people have told me that senior campaign officials and respected Republicans not affiliated with the campaign had contacted Grenell over the weekend to try to persuade him not to leave. In the weeks since Grenell’s hiring was announced, the campaign did not put him out to comment on national security matters and did not use him on a foreign policy conference call with journalists. People familiar with the situation told me that Grenell decided to resign because he felt he was being kept under wraps at a time when national security issues, including the president’s ad concerning Osama bin Laden, were front and center.

Despite the controversy Grenell’s hiring sparked in social media and conservative circles, there was no public statement of support for Grenell by the campaign and no supportive social conservatives were enlisted to calm the waters.

Grenell declined to comment Tuesday beyond a statement that noted in part: “[M]y 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.”

Recent reports in two conservative publications, National Review and the Daily Caller, reflected the uproar among some social conservatives over Grenell’s appointment. Although Grenell also raised the ire of liberal commentators with tweets about certain prominent women — that have since been deleted from Twitter — none of the people I spoke with mentioned the tweets as a factor in his decision to resign. Writing in National Review on Friday, Matthew J. Franck asked: “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?”

The argument that Grenell could not be openly gay and serve on a GOP presidential campaign was belied by the fact that Grenell’s past jobs include working for such foreign policy figures as the George W. Bush administration’s ambassador to the United Nations, John Bolton.

The pressure from social conservatives over Grenell’s appointment and the Romney campaign’s reluctance to send him out as a spokesman while controversy swirled left Grenell essentially without a job.

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

This was perhaps too subtle a retort to those calling for Grenell’s head, reminding them that Grenell was hired to advise not on gay issues but on foreign policy matters.