Do Presidential Approval Ratings Really Matter in Midterm Elections?

The good news for Democrats: President Barack Obama‘s relatively low approval rating might not matter in the midterm elections as much as some think.

The bad news for Democrats: Even a high approval rating might not be enough to save them.

The party that controls the White House is typically dealt a blow in the midterm election that comes in a president’s second term, ranging from a mild loss to an all-out “thumpin,” as President George W. Bush once said.

Just 42% of Americans approved of Mr. Obama’s job performance...