WRAPUP 11-Edwards backs Obama's White House bid

* Obama gets major endorsement from Edwards

* Clinton says race is not over yet

* Obama looks ahead to McCain

* Five nominating contests remain (Adds quotes from Obama campaign plane)

By Jeff Mason

GRAND RAPIDS, Mich., May 14 (Reuters) - Former U.S. presidential candidate John Edwards endorsed Democrat Barack Obama on Wednesday, giving a major boost to the Illinois senator's effort to unify the party behind his bid for the White House.

Edwards, the 2004 vice presidential nominee, had been heavily courted by both Obama and rival Hillary Clinton.

"The reason I am here tonight is the Democratic voters in America have made their choice and so have I," Edwards, who dropped out of this year's Democratic race in January, said at a rally with Obama in Grand Rapids, Michigan.

"There is one man who knows in his heart that it is time to create one America, not two, and that man is Barack Obama," he said, as Obama sat on a stool behind him.

The long-awaited endorsement helped blunt the impact of Clinton's landslide 41-point win over Obama in West Virginia on Tuesday. That result barely put a dent in Obama's lead in the Democratic race for the right to face Republican John McCain in November's presidential election.

Obama has an almost unassailable advantage in delegates who will pick the nominee at the party's convention in August, and has turned his attention to a general election match-up with McCain for the past week.

"I have no doubt that John Edwards can be extremely helpful to us campaigning in every demographic," Obama told reporters on his plane, adding that he hoped to get Edwards' delegates, estimated to number about 18, as well.

He said Edwards would "be on anybody's short list" for the vice presidency but said further comment would be premature.

Obama gained the support of four more superdelegates -- party officials free to back any candidate -- as well as the abortion rights group NARAL Pro-Choice America on Wednesday.

Edwards praised Clinton's "strength and character" but said it was time for Democrats to unite against McCain. He called Obama on Tuesday night to tell him he was ready to make the endorsement, an Obama aide said.

The backing of Edwards could help Obama attract white working-class voters who have flocked to Clinton in recent contests. The former North Carolina senator made a populist economic agenda on behalf of lower and middle income workers a centerpiece of his presidential bid, and has focused heavily on efforts to battle poverty.