PRESIDENTIAL FRUSTRATION BUBBLES OVER…. Reader B.A. emailed the other day to ask whether President Obama, who still enjoys very high approval ratings among rank-and-file Democrats, is aware of the discontent among those on the engaged, activist-minded left.

After this afternoon, I’m comfortable drawing a conclusion: Yep, he’s aware of it.

The president hosted a press conference this afternoon, ostensibly focused on making the case in support of his tax policy agreement with congressional Republicans. Along the way, he took some stern rhetorical shots at his GOP adversaries, comparing their tactics to hostage takers, blasting their misguided priorities, characterizing them as obsessed with tax breaks for the rich, and vowing to surprise congressional Republican leaders who might think they can push him around in the next Congress.

Visit for breaking news, world news, and news about the economy

But it was his remarks about left that will likely end up generating the most attention.

The last question from the presser was from the Wall Street Journal‘s Jonathan Weisman, who asked Obama to try to reassure those on the left about his “core values.” The president’s response, which was nearly eight minutes long, showed flashes of anger we’re not generally accustomed to seeing.

“This is the public option debate all over again,” Obama said. “I pass a signature piece of legislation where we finally get health care for all Americans — something that Democrats have been fighting for for 100 years. But because there was a provision in there that they didn’t get, that would have effected maybe a couple of million people, even though we got health insurance for 30 million people, and the potential for lower premiums for 100 million people, that somehow that was a sign of weakness, of compromise.

“If that’s the standard by which we are measuring success or core principles, then let’s face it: we will never get anything done. People will have the satisfaction of having a purist position, and no victories for the American people, and we will be able to feel good about ourselves and sanctimonious about how pure our intentions are and how tough we are.

“And in the meantime the American people are still saying to themselves, ‘I’m not able to get health insurance because of pre-existing conditions.’ Or not being able to pay their bills because their unemployment insurance ran out. That can’t be the measure of how we think about public service. That can’t be the measure of what it means to be a Democrat.”

He added that by this standard, Social Security and Medicare, given their limited scope when first passed, were both “betrayals of some abstract ideal.”

The president went on to say, “My job is to make sure that we have a North Star out there — what is helping the American people live out of their lives? What is giving them more opportunity? What is growing the economy? What is making us more competitive? And at any given juncture there’re gonna be times where my preferred option, what I’m absolutely positive is right, I can’t get done. And so then my question is, does it make sense for me to tack a little bit this way, or tack a little bit that way, because I’m keeping my eye on the long term, and the long fight, not my day to day news cycle, but where am I going over the long term?

“And I don’t think there’s a single Democrat out there, who if they looked at where we started when I came into office and look at where we are now, would say that somehow we have not moved in the direction that I promised. Take a tally, look at what I promised during the campaign. There’s not a single thing that I said that I would do that I have not either done or tried to do. And if I have not gotten it done yet, I’m still trying to do it.”

For quite some time, it’s been clear that the president feels as if he hasn’t gotten the credit he believes he deserves from his base. I think that frustration bubbled over this afternoon.

Our ideas can save democracy... But we need your help! Donate Now!

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.