There’s no more persistent storyline in Democratic politics these days than the one that goes something like this: Liberals, the foundation of President Obama’s 2008 victory, have grown increasingly disenchanted with him over the intervening years and might not be there for him in 2012.

U.S. President Barack Obama looks down while speaking at a bill signing ceremony promoting jobs for veterans at the White House in Washington November 21, 2011. REUTERS/Kevin Lamarque

But, with the exception of the liberal pundit class (and some major donors), there doesn’t appear to be any broad scale erosion from the base coalition that helped Obama win in 2008.

“There is a difference between the liberal pundit class of Washington, New York and [Los Angeles] and the mainstream, middle America base of progressive, younger voters who surged to the polls and changed the face of the electorate in 2008,” said Cornell Belcher, who conducts polling for the Democratic National Committee.

We explored the Obama base erosion myth more deeply in in our Monday newspaper column. We wrote:

“There is one immutable fact about President Obama’s reelection chances: Nobody has a more solid 44 percent base than he does,” Democratic pollster Peter Hart wrote in a not-entirely-uncritical memo assessing the state of political affairs a year out from the election.

As evidence, Hart noted that in the latest NBC-Wall Street Journal poll, Obama takes 44 percent in a three-way race with former Massachusetts governor Mitt Romney as the Republican nominee and Rep. Ron Paul (R-Tex.) running as an independent; has a 44 percent job approval rating; and has a 45 percent positive personal rating. In the same survey, 45 percent said they “probably” will vote for Obama in 2012.

At the heart of the president’s enduring strength among his base are African Americans who have never wavered in any meaningful way after 95 percent of black voters opted for the Illinois senator in 2008.

In Gallup’s latest weekly tracking polling, Obama’s job approval rating stands at 43 percent among the general public but is nearly double that — 84 percent —among African Americans. In the November NBC-WSJ poll, Obama’s approval rating among black voters stood at a stratospheric 91 percent.

Given that African Americans made up 13 percent of the overall electorate in 2008 — and, hence, a much larger chunk of the Democratic base vote — Obama’s continued support among that key demographic makes any sort of widespread base erosion in 2012 unlikely.

While the numbers are, well, the numbers, we got an interesting email in response to our column from a senior Democratic strategist who offered a slightly nuanced take on Obama’s base issues (or lack thereof).

“Obama doesn’t have the base problem the press thinks he has, with liberals,” the Democratic source wrote. “To the extent there is a base problem, it is with white working class voters who traditionally vote Democratic and thought the change they were voting for in 2008 was change in the economy, which of course hasn’t come.”

The question is whether — and to what extent — white working class voters remain an integral part of the Democratic base. In 2008, Obama lost among white voters by eight points (including every age demographic except 18-29 year old whites) and still won a sweeping national victory over Arizona Sen. John McCain.

Next November’s election may answer that question. In 2008, Obama swept the Rust Belt states (think Ohio, Wisconsin, Michigan, Pennsylvania) that have lots and lots of white working class voters in them. This time around his political footing is far less firm in each.

Victory in a majority of the Industrial Midwest likely means a second term for Obama. Defeat makes for a much tougher path to re-election.