Comeback? If this is a comeback, I sure wouldn't want one.
Did you miss the election results this week? Those polls were pretty definitive.
John Kennedy - 70.1% (did not finish term - assassinated)
Dwight Eisenhower - 69.6% (re-elected)
George W. Bush - 62.2% (re-elected)
George H.W. Bush - 60.9% (defeated)
Richard Nixon - 55.8% (re-elected)
Ronald Reagan - 50.3% (re-elected)
Lyndon Johnson - 50.3% (did not run for second term)
Bill Clinton - 49.6% (re-elected)
Gerald Ford - 47.2% (defeated)
Jimmy Carter - 45.5% (defeated)
Harry Truman - 45.4% (narrowly re-elected)
Barack Obama - currently 39% (and dropping)
It remains to be seen what Obama's final average approval rating will be before his first term is over but as you can see, it is not looking good for him historically. Only Clinton and Truman were able to be re-elected with less than a 50% approval rating and that is only because they had very weak opponents (Dole and Dewey).
So long as the GOP puts up a strong opponent, it looks pretty dismal for Obama's re-election chances.