WASHINGTON – It's official: President Obama will clinch the Democratic nomination for president Tuesday, ending a low-key primary race that many Americans probably didn't realize was happening.

Obama is certain to reach the 2,778 delegates he needs to secure his party nod for a second time when five states vote on Tuesday. He has won almost every delegate so far, with a few exceptions in some Southern states that won't vote Democratic in the fall anyway.

But don't expect a big party, or any party. Campaign officials say they are focused on the general election, as they have been for months, and the all-but-certain Republican nominee, Mitt Romney.

All this is a stark difference from four years ago.