The White House on Thursday defended its decision to significantly expand the ranks of public relations specialists on the executive payroll during President Obama's time in office, and cast it as a transparency exercise that's needed to ensure officials are communicating "effectively" to the public.

The Obama administration has spent more than $1.5 billion on government public relations staffers a year, as well as additional private-sector communications specialists, since the president took office, according to a Government Accountability Office report released Wednesday.

The White House's chief spokesman, Josh Earnest, defended the move and called it money well spent.

"The administration has made it a priority to interact with the public and interact with the press corps and to be as transparent as possible," Earnest told reporters Thursday, "and that is work that requires dedicated professionals who are interested in furthering that goal and helping the American people understand exactly what the administration is doing, what we have prioritized and what our success has been in implementing the agenda laid out by President Obama."

Earnest went on to defend the administration's communications "track record" as "pretty strong — both on the substantive [policy] progress that we've made, but also in terms of the effective way in which we've been able to communicate with the American public."

"I think the American public and our democracy is well served by that," he said before taking a shot at Republicans who are criticizing the taxpayer expense.

"There isn't much that we do around here that isn't the source of vociferous criticism from those on the right so they are certainly entitled to do that," Earnest added.

The administration added 667 public relations staffers between 2008 and 2011, bring the total communications staffing to 5,238 across all the federal agencies, the GAO said. The number has since decreased slightly to 5,100 in 2014, the last year for which the GAO had figures.

Sen. Mike Enzi, R-Wyo., chairman of the Budget Committee, requested the review and said the numbers are "crucial" in providing a snapshot on which agencies are spending the most.

The biggest-spending agency by far, according to the report, is the Department of Defense, which has spent an average of just under $630 million a year on PR in the past decade. It has more than 2,000 PR employees.

Health and Human Services was the only other agency to average more than $100 million annually in PR spending. Homeland Security, Commerce and Transportation rounded out the top five spenders.