Defending his new budget as one of "tough choices," President Barack Obama said Tuesday that more difficult decisions about the nation's biggest expenses – Medicare, Medicaid and Social Security – will have to be tackled by Democrats and Republicans acting together, not by White House dictates.

"This is not a matter of, 'you go first, I go first,'" he said. "It's a matter of everybody having a serious conversation about where we want to go and then ultimately getting in that boat at the same time so it doesn't tip over."

The president pitched his $3.73 trillion budget as a balance of spending on needed programs and significant reductions that would cut the deficit by $1.1 trillion over 10 years. The budget includes a mix of spending freezes on domestic programs, pay hike suspensions for federal civilian workers and new revenues from increased taxes on the wealthy and on oil and gas producers.