Is another Republican wave building?

Historically, Democrats have held an advantage of at least a few points on the generic ballot, even when election results are a wash: Democrats held a six-point edge just before Election Day 2000 and picked up a grand total of one seat. Democrats led Republicans by one point on the generic ballot just before the 2010 elections, when Republicans rode to a sweeping victory.

And there’s no sign that Obama will become more popular. Presidents who see their approval ratings dip so dramatically in the second term rarely see their numbers improve. Lyndon Johnson and Richard Nixon’s approval ratings never recovered after the Vietnam War and the Watergate scandal (Nixon, of course, didn’t stick around to see just how far his ratings could fall). George W. Bush’s approval rating sank in the spring of 2005, and continued falling through the end of his term. Obama’s numbers are starting to resemble Bush’s trend lines.

For much of Obama’s tenure, even voters who say they disapproved of his job performance still retained a favorable impression of the president. That’s increasingly not the case: In the latest Washington Post/ABC News survey, conducted earlier this month, Obama’s unfavorable rating, 52 percent, tops his favorable rating, 46 percent. It’s only the second time [pdf] the number of unfavorable impressions outweighed the favorable ones.