In response to a White House mandate, the agencies and departments of the federal government are gradually moving their IT operations to the cloud in a shift that could save billions of dollars, while also raising serious security concerns. \n\nIn a new survey of federal IT managers, MeriTalk, an online community dedicated to government technology, charted the progress of agencies that have been shifting "mission-critical" applications to the cloud. Respondents flagged security as a chief area of concern in migrating to the cloud, with 73 percent indicating that issues such as data vulnerabilities and threat vectors are a primary barrier in shifting mission-critical apps to the cloud. Perhaps it follows then that the largest proportion of the study participants said that they prefer a private cloud over a hybrid or public model. Thirty-eight percent of the respondents told MeriTalk that they have shifted a mission-critical application to a private cloud, compared to just 11 percent who have made a similar move to a hybrid cloud and 10 percent who have engaged with a public cloud. The MeriTalk study comes as departments and agencies have been revamping their IT strategies in response to a number of directives from the White House and Office of Management and Budget pertaining to cloud computing and data-center consolidation, an ambitious agenda that seeks to cut costs and streamline the roughly $80 billion federal IT apparatus. Following on the "cloud-first" policy the Obama administration promulgated in 2010, the General Services Administration has recently been soliciting feedback from industry and government members for a program that would enlist cloud brokers to assist federal agencies with the transition of their systems and applications to private-sector providers. According to the new report, the government could save $16.6 billion if each agency shifted three applications deemed mission-critical to the cloud. Respondents to the survey indicated that more than half of their IT budgets are spent on supporting mission-critical applications. But the government's drive to the cloud, with all of its promised cost and efficiency benefits, has been slowed by significant obstacles. Beyond the persistent security concerns, federal IT managers told MeriTalk that 70 percent of their budgets are devoted to the maintenance of legacy applications, leaving scant resources available for cloud computing projects. Additionally, respondents reported that 52 percent of their mission-critical applications are custom-built, and 45 percent indicated that moving those apps to the cloud would entail a "major re-engineering." "Transitioning legacy, mission-critical applications to the cloud is not a forklift exercise -- in many cases it's more like an organ transplant," MeriTalk founder Steve O'Keeffe said in a statement, noting the respondents' preference of a private cloud over the public and hybrid alternatives. "With the complexity and security concerns, it's not surprising many agencies want a private room." The survey also revealed what might be described as tepid support for the cloud, broadly. A strong minority, at 46 percent, said that placing mission-critical applications in the cloud would help them execute their business tasks, while 43 percent indicated that the cloud would help their analytics for big data applications. Nevertheless, the transition seems inevitable, if incremental. In aggregate, respondents projected that 26 percent of their mission-critical applications would reside in the cloud within two years, rising to 44 percent in five years. Kenneth Corbin is a Washington, D.C.-based writer who covers government and regulatory issues for CIO.com. Follow everything from CIO.com on Twitter @CIOonline, on Facebook, and on Google +.