Even as Barack Obama and Hillary Clinton continue to slug it out in the final few Democratic primaries, most observers believe whichever candidate emerges from the primaries already has the inside track to the White House. Due to a number of Republican weaknesses, 2008 is supposed to be the Democrats’ year.

But before Michelle Obama starts measuring the White House for new drapes, we may want to take a look at historical precedent. As any school child used to know, the first Republican to win a Presidential election was none other than Abraham Lincoln. From that initial success, the GOP has done quite well in Presidential elections, winning 23 contests compared to just 14 for the Democrats during the same period.

In fact, Howard Dean may scoff, but since the Civil War only four Democrats—Jimmy Carter, Lyndon Johnson, Franklin Roosevelt, and Samuel Tilden—have won a majority of the popular vote. One of those, Tilden in 1876, lost the Electoral College vote anyway and never did become President.

The last Democratic candidate to win a majority of the popular vote was Carter, who commanded a whopping 50.1 percent of the votes cast in 1976. That’s right. It has been 32 years since a Democrat won a majority of the popular vote. Carter defeated Republican incumbent Gerald Ford, the man who pardoned Richard Nixon and carried the burden of Watergate and the Vietnam War into the election.

Obviously, 1976 was not a good year to be a Republican. Nixon’s disgraceful resignation and reputation for deceit and corruption fatally wounded the Republican Presidential ticket. But even with such enormous advantages on his side, Carter barely eked out a majority and beat Ford by just two percentage points. Carter’s once sizeable lead in the polls dwindled as election day drew near, so much so that some observers believe that had the election taken place a couple of weeks later, Ford may well have prevailed.

Like the 1976 contest, all conditions point toward an easy Democratic victory this November. President George W. Bush, the Republican incumbent, suffers from abysmal approval ratings—below 30 percent in some polls. The economy is weak and appears to be entering a recession. And the presumptive Republican nominee John McCain, while certainly something of a maverick, is quite close to the President on the one issue causing him the most damage—the war in Iraq.

And yet right now in a hypothetical head-to-head match-up, McCain and Obama appear to be in a dead heat. A recent USA Today/Gallup poll shows Obama leading by 3 points, while the latest Rasmussen tracking poll shows McCain up by 3. A McCain-Clinton match-up is also too close to call at this point. If this is a Democratic year, one wonders what a Republican year would look like.

The fact is Democrats historically have struggled to win the White House and have found ways to lose contests that presumably they should have won. Since Lincoln, Americans have tended to see the Presidency as primarily a Republican institution. It is not that Democrats cannot win, but they seem to have more negative voter assumptions to overcome.

As this year’s Democratic primaries move toward a conclusion, party leaders are hoping that Barack Obama will become the next Franklin Roosevelt. But if history is a reliable predictor, he could just as easily become the next Samuel Tilden.