Riedl said the impact will be limited because most of the money for education, police and fire comes from local and state governments, including 90% of K-12 education funding.

For all the debate about the deficit in Washington, bond market yields in the U.S. are lower now than when the government was running a budget surplus a decade ago, even though Treasury data show the amount of marketable debt outstanding has risen to more than $9 trillion from about $4.3 trillion in mid-2007.

The budget doesn't provide specific cuts. It sets a cap, and the Appropriations Committee has to come up with detailed plans in the coming months.

The Congressional Budget Office said in an April report that Ryan's plan "specifies a path" that would cause government spending outside of Social Security, Medicare, Medicaid and interest to drop to 6% of the gross domestic product in 2022 from 12% in 2010. Spending in that category has exceeded 8% of GDP in every year since World War II, the nonpartisan agency said.

'Lot of Pressure'

As the population increases it becomes more difficult to provide services with less money, said Robert Bixby, executive director of the Concord Coalition, which promotes balanced budgets. Republicans will be hard-pressed to keep up the level of cuts for five years, Bixby said.

"They will get a lot of pressure from people back in the district -- business leaders, educators, doctors, hospitals," he said. "You are going to hear from the hometown interests that the federal government isn't doing enough to help the local economy."

A coalition of Christian leaders has formed a group called "Circle of Protection" to prevent cuts in programs that help the poor and needy.

"If you come after the poor, you will have to go through us first," Reverend Jim Wallis, an evangelical author, said on a conference call with reporters.

Chris Hansen, president of the American Cancer Society Cancer Action Network, said volunteers are stepping up efforts across the country to prevent cuts to biomedical research at the National Institutes of Health and cancer-prevention programs at the Centers for Disease Control and Prevention.

Republicans had proposed a $1.6 billion reduction in the $31 billion NIH budget for this year. That was scaled back to $260 million in negotiations with Democrats.