The federal government has identified 100 data centers that could be shuttered by the end of the year as part of an effort to shrink its total data center count by more than one-third by 2015.

The government is also getting ready to move about 75 agency-identified programs to cloud — or Web-based — computing to comply with the new “cloud-first” policy, said Vivek Kundra, the federal chief information officer, at a hearing last week.

Kundra has made data center consolidation and a shift of technology to the cloud key focuses of his effort to change federal information technology spending. Cloud advocates say moving more programs to the Web allows servers to be used more efficiently and requires fewer data centers.

Since releasing a 25-point implementation plan last year, Kundra has required quick action, calling on agencies to identify unneeded data centers and programs that make good candidates to move to the cloud.

Appearing on Capitol Hill last week, Kundra said he expects resistance once the Office of Management and Budget identifies the specific data centers to be closed. The government has just under 2,100 data centers — meaning both owned and leased centers larger than 500 square feet — and plans to close 800 of them.

David A. Powner, director of information technology management issues at the Government Accountability Office, said the goal of shutting down 800 in just a few years is a “stretch goal.”

“Stretch goals are good,” he said, but “when you start looking at the complexity of moving centers and consolidating . . . it’s just not necessarily an easy thing to do.”

In the case of shifting to the cloud, Kundra said agencies are now looking at issues like security requirements and procurement strategies as they prepare to move the 75 identified programs.

Powner backed the data center and cloud goals but said executing the changes will be far more challenging.

“Now we need to get to implementation and that’s really where the rubber’s going to meet the road,” he said.

The GAO has challenged the accuracy of the IT Dashboard, a publicly available Web site that compiles data on federal agencies’ IT programs. The site has been a key part of Kundra’s reform strategy; he has said the site injects much-needed transparency into the government’s spending.

In a report released last month, the GAO said the site is improving but still has major inaccuracies. The report criticized agencies for providing erroneous data, and the OMB for miscalculating ratings of how well the programs have stuck to their budgets and schedules.