It is only in comparison to today's Republican Party, divided between its old-school establishment and its tea party zealots, that today's Democrats look unified.
In fact, as President Obama prepares to face whomever the Grand Old Party nominates from its generous array of 2012 candidates, he needs to watch his back. A familiar faction is dragging down his approval ratings: disgruntled liberals.
For example, the Senate's only self-identified socialist, independent Bernie Sanders of Vermont, went so far in recent days as to suggest, "It would be a good idea if President Obama faced some primary opposition" to nudge him back into focusing on his base before the general election.
That's bold. Yet, significantly, Sanders was not offering himself to be that opposition. That's probably wise. Any serious candidate who runs against Obama in Democratic primaries runs the risk not only of losing but also dividing the party and increasing the chance of a Republican victory.
Still, the drive for unity on the left has not deterred two prominent progressive voices, TV talk-show host Tavis Smiley and Princeton professor Cornel West. The two best-selling authors, who also co-host a radio show, have announced a 15-city "Poverty Tour" beginning today, taking their long-running hold-Obama-accountable campaign to the streets.
West, a leading endorser of Obama in 2008, has turned critic, going so far in recent months as to label the president a "black mascot of Wall Street oligarchs." Smiley similarly complains that Obama talks a lot about the middle class but does too little for the nation's poor, even though "the new poor are the former middle class."
A new ABC/Washington Post poll (conducted July 14-17) that finds "the number of African-Americans who believe the president's actions have helped the economy has dropped from 77 percent in October to just over half of those surveyed."
Why the drop? Probably for many of the same reasons that self-described liberal Democrats who "strongly support" Obama's record on jobs plunged 22 points in the ABC/Post poll -- to 31 percent from 53 percent last year.
When Obama's popularity among blacks -- who gave him 96 percent of their vote in 2008 -- is catching a cold, it is a sign that the rest of his base is coming down with pneumonia.
The overwhelming issue is still "the economy, stupid," as Bill Clinton's team used to say in his 1992 presidential campaign. These days the economy is not getting better fast enough to please anyone except perhaps those who make money off of home foreclosures.
Yet Obama, no novice to political and social realities, shows no signs of changing course from his past approach: build a broad coalition with crucial middle-class swing voters by fighting poverty based on income and opportunity, not race.
Asked about West's criticisms, Obama told NPR host Michel Martin, "I wake up every morning trying to promote the kind of policies that are going to make the biggest difference for the most number of people."
That's wise. Every election, I once heard political strategist James Carville say, is a contest between "change" and "more of the same." Obama, like Clinton, won with a "change" campaign. If high unemployment persists next year, Obama will have to show that as a nation we are, at least, on the right path -- as Franklin D. Roosevelt did in 1936.
Happy days are not here again, to paraphrase a popular Roosevelt-era campaign song, but Obama has to show that he's the best choice to get us there.
In that spirit, he can reach back to Abraham Lincoln's 1864 slogan: Don't swap horses in midstream.