Don’t get cocky, Dems: History suggests that there are plenty of ways for the Democrats to lose the 2008 presidential election, says Rutgers historian David Greenberg in an essay published in The Boston Globe’s “Ideas” section. “The Republicans possess certain advantages that are too often overlooked, including a built-in edge in the electoral college, Bush’s impending exit from the political picture, and several candidates with potential across-the-board appeal,” Greenberg writes. He later adds:

The first myth to dispel is that of Democratic momentum. It’s tempting to regard the Democrats’ 2006 triumphs as rock-hard proof that a new liberal wind is blowing. But as a historical matter, the party that wins the Senate or House in an off-year election has no discernible advantage when seeking the presidency two years later.

In 1948, two years after seizing control of Congress, the Republicans not only failed to oust Democrat Harry Truman from the White House but even ceded back control of both chambers. In 1988, two years after regaining the Senate, Democrats still couldn’t capture the presidency. Indeed, not since 1920 has either party taken the presidency after winning control of Congress in the preceding midterms — a historical tidbit that, if statistically trivial, warns against making any assumptions about 2008.