Barack Obama’s election in 2008 was a remarkable victory. With a 7.2% lead in the popular vote and 192-vote lead in the Electoral College, Obama seemed to break the razor-thin margins of the previous two elections in favor of the Democrats.

But that success is unlikely to be repeated. A weak economy and a skeptical electorate (60% of Americans think the country is “on the wrong track,” according to a late July NBC News/Wall Street Journal poll) promise a tough battle for the incumbent president.

This reality is not lost on the Obama campaign. As the president himself noted at a Seattle fundraiser in May, “this election is actually going to be even closer than the last. And the reason for that is that too many of our friends and neighbors are still hurting because of this [economic] crisis. And they see what’s going on in Washington, and they don’t like it. So there’s just a frustration level there that will express itself in the election.”

In 2008, Obama won nine states that had voted Republican in 2004, garnering a 113-electoral-vote swing to the Democrats. That’s a hefty portion of the 270 electoral votes required to win the White House.

But Obama’s victory was due in no small part to the financial crisis that started in the late summer and early fall of 2008. The two largest swing states in 2008, Florida and Ohio, had polled a McCain victory in the summer, and switched to Obama in the fall, after the financial crash.

Popularity down

Obama’s popularity figures have gone down since that election. From 52.9% of the popular vote in 2008, Obama now averaged just 46.3% in a RealClearPolitics average of polls from mid-July.

As Republican pundits have noted repeatedly, no presidential incumbent has ever won reelection with a lower percent of the popular vote in the second election than he got in the first.

Of course, the polling average does not reflect turnout. Even in the excitement of the 2008 election, only 63% of the American electorate turned out to vote. Will the tally of those who actually show up at the polling booth reflect Obama’s relatively poor showing in the national polls? Put another way, will the country’s economic troubles hinder the president’s efforts to mobilize and excite supporters?

Economic troubles not going away

As with popularity, so with unemployment. No incumbent president in living memory has won reelection with an unemployment rate as high as the current figure of 8.2%. Not George W. Bush, with 5.5% unemployment during his reelection race in 2004, not Bill Clinton with 5.4% in 1996, not even Ronald Reagan with the relatively high 7.5% in 1984.

Unemployment is even higher in crucial swing states such as Florida (8.6% unemployment), Nevada (11.6%) and North Carolina (9.4%). And the situation may only get worse by Election Day, as the Bureau of Labor Statistics reports that unemployment rose in 27 US states in June, and fell in just 11.

The situation was summed up succinctly by President Obama’s own treasury secretary, Tim Geithner, in testimony before Congress this week.

“The economy is not growing fast enough. Unemployment is very high,” Geithner said. “There’s a huge amount of damage left in the housing market. Americans are living with the scars of this crisis.”

Demographic advantage for Republicans

While Obama continues to show a slight lead in polls that track the popular vote, the American presidential election is not decided by a national poll, but by a series of state elections in which the winner takes all the electoral votes of that state, apportioned by population. Thus, any ballot that is not part of the majority vote in each state is effectively erased in the final tally.

While Democrats hold out high hopes for long-term growth in nationwide support because of their advantage among young and immigrant voters, the more immediate calculus of population growth is shifting electoral votes to staunchly Republican states, thus effectively giving the Republican candidate more electoral votes without Obama having to sway any additional voters.

In the wake of the 2010 census, the Republican strongholds of Texas, South Carolina and Georgia saw a combined gain of six electoral votes in the 2010 census, while staunchly Democratic states New York, New Jersey, Michigan, Massachusetts and Illinois lost a combined six votes.

The total shift, once all changes are accounted for, is six votes to Republican-leaning states, amounting to a small 12-vote advantage for Republicans compared with 2008.

That figure may seem insignificant compared to the 192-vote lead Obama enjoyed in 2008, but 2012 will likely look less like 2008 and more like 2000, when Republican George W. Bush defeated Democrat Al Gore by just five electoral votes out of 538, despite losing the popular vote. In such a close race, the 12-vote advantage conferred by the new census data could be decisive.

In the final analysis, Obama can still win. He continues to enjoy a slight lead over Republican challenger Mitt Romney in a majority of nationwide polls. But as election day nears and American voters begin to pay closer attention to the debates on the economy and other issues, Obama will likely find that victory in 2012 won’t be nearly as easy as last time.