WASHINGTON — The Air Force’s top general appeared to be losing his cool. But it wasn’t over a controversial plan to scrap an aircraft prized for protecting ground troops or billions of dollars in cuts that are straining a service striving to recover from the grind of 12 years of war.“The single biggest frustration I’ve had in this job is the perception that somehow there is religious persecution inside the United States Air Force,” Gen. Mark Welsh III told the House Armed Services Committee during a hearing this year. “It’s not true.”Welsh’s irritation underscored the pressure the Air Force is under from Republicans in Congress, evangelical Christians and conservative advocacy groups to end what they allege is the service’s suppression of religious freedom. Their charge isn’t new, but the target is: a regulation designed to prevent religious bias by barring commanders and other leaders from “the actual or apparent use of their positions to promote their religious convictions to their subordinates.”The controversy represents the latest chapter in the Air Force’s years-long struggle to balance the constitutional right of freedom of faith with the Constitution’s prohibition on the governmental promotion of religion.“The Air Force religious freedom regulations and practices are inconsistent with the Constitution and with current law,” 20 House Republicans wrote in an April 15 letter to Air Force Secretary Deborah Lee James. The regulation “introduces a subjective and unworkable restriction on a leader’s ability to speak about their faith.”The Air Force defends the regulation as a measure that “seems to make good sense.” Yet the pressure – legislation, congressional hearings, meetings, letters, media statements and online appeals – to revise or dump it is having an impact.Late last month, James and Welsh convened a “Religious Freedom Focus Day” conference of senior chaplains and legal and manpower officials to discuss the policy. Air Force spokeswoman Rose Richeson declined to make the results of the April 28 meeting public, saying it would be “too premature to provide an interview.”But Tony Perkins, the president of the Family Research Council, a Christian conservative policy institute that leads a coalition of organizations that are fighting the regulation, said that based on what he heard from people at the meeting he expected the Air Force to “make a policy change shortly.”Pro-Christian bias?The prospect alarms supporters of the policy, who say that a pro-Christian bias in the Air Force remains overwhelming and that the regulation provides an avenue of relief to service members who object to being regaled with their superiors’ religious views or who worry that declining invitations to “voluntary” Bible classes might jeopardize their fitness reports and chances of promotion.The regulation has been “an umbrella in a tsunami of Christian fundamentalist extremism,” said Mikey Weinstein, the head of the Military Religious Freedom Foundation and a former Air Force officer whose outspokenness has won him scorn and death threats.Since the regulation went into effect, 4,121 Air Force personnel have sought the organization’s help in fending off proselytizing by superiors, Weinstein said. The organization has a 95 percent “success rate” in ending “the offending behavior,” he said. Evangelical Christians draw the largest number of complaints – ironically enough, from fellow Christians, he said.There’s little disagreement about the importance that the free practice of religion plays in ensuring the cohesion, morale, “good order and discipline” of military units. But the regulation says superiors who proselytize “may cause members to doubt their impartiality and objectivity.”The regulation grew out of a 2005 uproar over proselytizing by evangelical Christians and Weinstein’s allegations of religious discrimination at the U.S. Air Force Academy, at Colorado Springs, Colo.