For months, President Obama has heard grumbling from his left.

He caved on a public option for health care, liberals complained. He escalated the war in Afghanistan and failed to close the military prison at Guantanamo Bay. He let millionaires and billionaires keep their Bush-era tax cuts. He agreed to budget cutting without putting up a fight, and he dithered on gay rights

That was the rap anyway, not only on the substance of issues but in the way progressives were treated by the Obama White House – “with contempt,” former Democratic National Committee Chairman Howard Dean told a Monitor breakfast in January. Dean blamed “a group of senior advisers around the president who … thought they knew everything and we knew nothing.”

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To many on the left, this seemed especially true in the way Obama handled budget cutting – rolling over on programs liberals hold dear.

“His political strategists seem to believe that he can win reelection by positioning himself as being conciliatory and reasonable, by always being willing to compromise,” Paul Krugman wrote in the New York Times a week ago. “But if you ask me, I’d say that the nation wants … a president who believes in something, and is willing to take a stand. And that’s not what we’re seeing.”

Using a boxing analogy, Daily Beast columnist Eric Alterman observed “a fundamental fact of politics …nobody ever won a fight by turning the other cheek.”

Well, it seems Obama has decided to take off the gloves – at least rhetorically.

With key Republican lawmakers seated a few feet away from him the other day, he lambasted the GOP budget plan for FY 2012.

“There’s nothing serious about a plan that claims to reduce the deficit by spending a trillion dollars on tax cuts for millionaires and billionaires,” Obama said in his speech Wednesday at George Washington University. “And I don’t think there’s anything courageous about asking for sacrifice from those who can least afford it and don’t have any clout on Capitol Hill.”

Then he laid out his own vision – one distinctly different from his opponents’ in the Republican-controlled House, especially its tea party wing. For one thing, he stated flatly that he would not again let the Bush-era tax cuts for the wealthy remain law – which means raising taxes.

How did it play with his liberal base?

Columnist Krugman called it a “great relief” for progressives, “a reaffirmation of American compassion and community.”

"Americans will be very glad to hear that the President supports raising taxes on the rich,” said the Progressive Change Campaign Committee in a statement.

Still, Obama’s new-found political aggression – echoed in his Saturday radio address and sure to be heard in this coming week’s town hall meetings – is not enough for some on the left.

“With the richest 1 percent of Americans taking home a quarter of all income and facing the lowest tax rates in generations, we need to go much further to make sure millionaires and corporations pay their fair share, and Wall Street banks help clean up the mess they created,” said Justin Ruben, executive director of MoveOn.org.

And some commentators – including labor union leaders, who were only mildly approving of Obama’s speech – seemed to be summoning the ghost of FDR’s New Deal.

“At a time when House Republicans are talking up the notion of raising the retirement age to 70 and otherwise reducing benefits and imposing budgets on the elderly, the president is expressing a willingness to negotiate away a lot of what is social and secure about Social Security,” writes John Nichols, Washington correspondent for The Nation. “That's unsettling.”

Obama has officially kicked off his reelection bid. His speech at George Washington University was part of that, as was his fund-raising event the other night with its open-mic blooper in which he snarkily had at House Republicans in general and Budget Committee Chairman Rep. Paul Ryan in particular.

There’ll be more of that as he works to solidify his base for one more “Yes We Can.”

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