Ronald Reagan is respected among most Americans as a president who tore down the Iron Curtain, ushered in a 15-year bull market, and generally restored optimism. Even Barack Obama admitted in 2009 that "I think Ronald Reagan changed the trajectory of America."
Unemployment was also worse during Reagan's first term that it is during Obama's. The first map from the Bureau of Labor Statistics
below shows regional unemployment in October 1982, right before Reagan's Republicans lost 26 seats in the midterms
. The second map shows the most recent unemployment map available, from August 2010.
This probably doesn't mean that Democratic bleeding will be limited to 26 seats (larger cultural factors are at work), but it does mean that Obama has plenty of time after the midterms to rescue his presidency. And while Obama-Boehner may not have the charm of Reagan-O'Neill, it'll surely help the White House to differentiate its policies from Congress.