Romney told the American Society of News Editors convention in Washington -- where Obama assailed the former Massachusetts governor and the Republican Party the day before -- that Obama was withholding critical information about actions he intends to take if he wins a second term.
"He doesn't want to share his real plans with the American public," Romney said. "His intent is on hiding. You and I are going to have to do the seeking."
Romney recalled Obama's March 26 private comment to outgoing Russian President Dmitry Medvedev, picked up by a live microphone, that he would be "more flexible" on foreign policy after the election.
"That incident calls his candor into serious question," Romney said, and he asked what other plans Obama would disclose only if he is re-elected and "no longer accountable to the voters."
"With all the challenges the nation faces, this is not the time for President Obama's hide-and-seek campaign," Romney said.
Obama told the journalism group Tuesday -- hours before Romney won three primary contests that gave him a nearly 400-delegate lead over former U.S. Sen. Rick Santorum of Pennsylvania in the Republican presidential race -- that the federal budget adopted by House Republicans was a "Trojan horse" that would greatly deepen U.S. income inequality.
He labeled the plan, drawn up by House Budget Committee Chairman Paul Ryan, R-Wis., "social Darwinism" and lashed out at Romney for supporting it.
Obama singled out the GOP plan for Medicare, claiming its shift to a voucher system would drive up healthcare expenses for the elderly, since private insurance companies would target the youngest and healthiest people and leave the rest to rely on Medicare.
Romney told the journalists Wednesday his plan is to preserve Medicare and Social Security for current or near retirees, and make sustainable changes to allow the programs to benefit future generations.
"I'd be willing to consider the president's plan, but he doesn't have one. That's right, in over three years he has failed to enact or even propose a serious plan to solve our entitlement crisis," Romney said.
White House spokesman Jay Carney said Obama's remarks Tuesday provided "a comprehensive, detailed -- dare I say, wonky -- exposition of his views of what our budget priorities ought to be and his views on why the Republican budget put forward by Chairman Ryan is not the right solution."
A wonk is a person preoccupied with an issue's arcane details or procedures.
Without mentioning Romney by name, Carney said, "The Ryan Republican budget would become the law of the land if someone else were to occupy the Oval Office next year and if Republicans continue to effectively control Congress."
He added the Ryan and Romney position on key American issues is no longer "the idea of a rump faction of the Republican Party."
"This is what now is mainstream Republican thinking," he said.
Romney, who later Wednesday campaigned in the Philadelphia area, was to venture into the central part of the state to campaign in Harrisburg and Scranton Thursday.
A fresh poll from Quinnipiac University shows Santorum leading Romney in Santorum's home state 41 percent to 35 percent among likely voters. U.S. Rep. Ron Paul of Texas came in at 10 percent, followed by former U.S. House Speaker Newt Gingrich of Georgia at 7 percent.
The March 27-April 1 phone survey of 647 likely Republican primary voters had a probable margin of error of 3.9 percentage points.