Earl Gibson III/AP Photo

After weeks of taking the heat from key constituencies, and trying gently to calm them down, President Obama has adopted a more forceful tone, calling on members of his base to get in line.

In a number of speeches over the past few days, Obama has publicly dismissed complaints from liberals over his handling of the economy, health care reform, and the environment, calling for unity at a time when he faces eroding popular support.

At a private California fundraiser Sunday night, Obama even exhorted the 300 top-dollar donors in attendance to “have some arguments with our progressive friends.”

“Even as we’ve gotten a huge amount done, there’s a lot of folks on our side who get dispirited because we didn’t get it all done in two and a half years,” he said. “That’s not how America works.”

The president recited a familiar list of accomplishments, voicing downright frustration that many have been overlooked with focus on what has been left undone.

“The notion that somebody is out of joint because we didn’t get a public option — come on,” Obama said, referring to a government-run health insurance program popular with some Democrats.

“No, we haven’t gotten everything done on the environmental front,” he added, “because we’re in the midst of a very tough economic time and people naturally are more hesitant about big changes at a time when they’re worried about their jobs.”

Obama says he believes the 2012 election will boil down to a choice between two clearly contrasting candidates – only one of which liberals and progressives will truly consider voting for: him.

“I expect all of you, again, not just to be supporting me; you have to be out there, active, engaged — just as engaged as you were in 2008,”  he said.

Obama told a crowd of several hundred supporters in Seattle earlier Sunday to “shake off any doldrums” and “talk to your friends and your neighbors and your coworkers – you need to tell them, you know, we’re not finished yet.”

On Saturday he told members of the African-American community and Congressional Black Caucus to “stop complaining. Stop grumbling. Stop crying.”

“Take off your bedroom slippers, put on your marching shoes,” Obama said.

It seem unlikely those liberal supporters on the sidelines will heed the advice quickly and enthusiastically, at least until there is a clear alternative to Obama they can rally against in 2012.

Some also say they find the dismissive tone from Obama — who famously urged progressives to hold him accountable — altogether perplexing or offensive.

“I’m not sure who the president was addressing. I found that language a bit curious,” Rep. Maxine Waters told CBS today.

Meanwhile, Obama’s approval rating among liberals – 67 percent, according to the most recent Gallup poll — remains higher than among any other group.