Frustration is mounting among defense officials about the lack of information on how across-the-board budget cuts could impact Wright-Patterson Air Force Base and Ohio defense contractors, U.S. Sen. Rob Portman said.

The White House Office of Management and Budget last week told the Pentagon to begin planning for sequestration, an expected average of a 9.4-percent across-the-board reduction to most defense programs.

“There’s some ways to mitigate the impact of this but we have no sense from the Pentagon that they will mitigate that,” said Portman, a Republican member of the Senate Armed Services Committee. “We have some really important national assets in Dayton that we are very worried about.”

Those key assets, among others, include the Air Force Research Laboratory, the post-graduate school Air Force Institute of Technology, and the 711th Human Performance Wing, home to the Air Force School of Aerospace Medicine, Portman said.

Wright-Patterson Air Force Base spokesman Daryl Mayer said the base hasn’t received enough information to speculate on how the reductions would impact the workforce or missions.

The Defense Department will confront nearly $500 billion in budget cuts over a decade starting in January if Congress and President Barack Obama fail by the end of the month to avert a “fiscal cliff” of automatic cuts, known as sequestration, and the expiration of Bush-era income tax cuts.

In the first year, the reductions would total about $55 billion to the U.S. military. That’s in addition to the $487 billion in cuts the defense budget will absorb the next 10 years, a compounded situation Pentagon leaders have warned would “hollow out” the nation’s defense.

Defense industry employees have grown more anxious with months of uncertainty and the fiscal cliff looming mere weeks away, said Deborah Gross, executive director of the Dayton Area Defense Contractors Association.

“I think people are more frustrated than they were before because in some sense we’re kind of hostage to the government getting their job done,” she said.

The Dayton association counts more than 250 defense contractors as members that employ a total of roughly 15,000 workers in the Miami Valley, she said.

Wright-Patterson ranks as Ohio’s largest single site employer with more than 29,000 military and civilian employees and a $4.7 billion annual economic impact, according to a report last year. The base supports nearly 36,000 jobs outside the fence with an economic impact of $1.5 billion, according to base figures.

Many contractors have postponed hiring decisions or additional spending and investments. “I think a lot of these companies are looking at these budgets and saying I need to be cautious because I really don’t know,” Gross said.

Army Lt. Col. Elizabeth Robbins, a Pentagon spokeswoman, said the Defense Department remains hopeful Congress and the president will pass a deficit reduction plan and avert sequestration.

“We are at the very start of this process and we don’t have the details firmed up but we think it’s prudent … at this stage that we begin at least some limited internal planning,” she said.

Sequestration would take time to happen so its effects would not be felt immediately, she said. “This is not a government shutdown. This is a sequestration, meaning we will have a smaller budget to carry out our mission and that will take some time.”