Kicking his campaign into high gear, President Obama on Tuesday said Republicans' vision of smaller government and lower taxes for the wealthy amounts to "thinly veiled social Darwinism," and cast his own fiscal blueprint, with its higher spending and taxes, as the way to sustain the social safety net.
The speech was as striking for its breadth of detail as for its fierce attacks on his potential rivals in November, and one Republican leader said Mr. Obama had become "unhinged."
Speaking to newspaper editors gathered in Washington, Mr. Obama derided Republican policies as failed "trickle-down" economics and said their budget would force seniors to pay more in health care costs, would shutter the country's national parks, and would push millions of poor mothers and children out of food assistance.
"Instead of moderating their views even slightly, the Republicans running Congress right now have doubled down and proposed a budget so far to the right it makes the Contract With America look like the New Deal," Mr. Obama said.
The president repeatedly painted himself as a moderate whose ideas would have been at home with Republicans just a few decades ago, but said the current Republican vision offers little room for compromise. He said voters will have to use the election to decide which direction the country will take.
Republicans were as harsh in their reply, pointing to the three years of trillion-dollar deficits Mr. Obama has overseen and mocking his budget, submitted in February, which the House defeated on a 414-0 vote last week.
"If the president were serious, he would put forward a plan to deal with our debt crisis and save Social Security, Medicare and Medicaid for future generations of seniors without raising taxes on small businesses that are struggling in this economy," House Speaker John A. Boehner, Ohio Republican, said in a statement. "Instead, he has chosen to campaign rather than govern, and the debt crisis he is presiding over is only getting worse."
Rep. Jeb Hensarling, chairman of the House Republican Conference, called the president's speech an "unhinged attack" and said it was "an act of desperation" designed to hide his own economic record.
House Republicans last week powered their own budget through their chamber on a 228-191 vote, with no Democrats supporting it. A separate vote on a bipartisan plan blessed by Erskine Bowles and Alan Simpson, who led a deficit commission in 2010, failed dramatically, earning just 38 votes of support.
Mr. Obama aimed his harshest barbs at the House Republican plan, written by Budget Committee Chairman Paul Ryan of Wisconsin and embraced by the party's presidential front-runner, Mitt Romney.
That budget calls for $5.3 trillion in spending cuts over the next decade, coupled with extending the Bush-era tax cuts across the board. It still leads to $3 trillion in deficits over the next 10 years, and doesn't bring the budget into full balance until almost midcentury — and only through offsetting tax increases and other spending cuts left unspecified in the document.
"It's nothing but thinly veiled social Darwinism," Mr. Obama said. "By gutting the very thing we need to grow an economy that's built to last — education and training, research and development — it's a prescription for decline."
The president targeted Mr. Romney for backing Mr. Ryan's plan, saying the former Massachusetts governor "is very supportive of this new budget and he even called it 'marvelous,' which is not a word you hear a lot when you're describing a budget," he said. "It's a word you don't often hear generally."
Mr. Romney fired back later Tuesday, telling radio host Sean Hannity the speech was a distortion of the truth.
"It's just astonishing to listen to him. I think the American people will have plenty of time to hear the charges and the countercharges and with the time they're going to have, they're going to recognize that what the president is saying about us is absolutely inaccurate and what he's saying about himself misrepresents the reality of his record," Mr. Romney said.
Darrell West, the director of governance studies for the Brookings Institution, said the president's speech reflects the deeply polarized political climate. General election candidates usually like to fuzz the differences between the parties and focus on appealing to centrist voters, he said.
"Both Romney and Obama have incentives to play to the base," he said. "Each of them needs a very strong turnout from committed people."
Because the unemployment rate is likely to remain at or above 8 percent for much of the year, Mr. Obama cannot claim to have resided over a full economic recovery. Instead, Mr. West said, he wants to take advantage of the tea party swinging Republicans to the right, accuse his opponent of extremism and avoid the election being cast as a referendum on him.
"If it's a referendum on him, he loses," Mr West said.
In his speech, Mr. Obama listed the areas where he said the Republicans' budget would lead to cuts, ranging from education, environmental protections and clean energy incentives to national parks and crime-fighting money within the FBI.
He acknowledged that those cuts aren't specified in the budget, but said those are the choices lawmakers will have to face, given the amount of government spending the GOP calls for.
"Perhaps they will never tell us where the knife will fall, but you can be sure that with cuts this deep, there is no secret plan or formula that will be able to protect the investments we need to help our economy grow," he said. "This is not conjecture. I am not exaggerating. These are facts."
By contrast, he said, wealthier Americans can afford a tax rise that would help continue funding all of those needs.
His own budget calls for tax rates on those in the highest tax brackets to return to the levels they were under President Clinton, and he also proposes a new "Buffett Rule" tax of a minimum tax rate on those making at least $1 million a year.
The tax is named after billionaire Warren Buffett, who has decried the fact that his investment income is taxed at a lower rate than the salary and wage income of his secretary.