WRAPUP 2-Obama plans Iowa trip with victory in sight

(Adds more details throughout, previous EUGENE)

By Jeff Mason

ROSEBURG, Oregon, May 17 (Reuters) - Hoping that a pair of contests in Oregon and Kentucky on Tuesday will allow him to essentially clinch the Democratic nomination, Barack Obama will make a symbolic return to Iowa, the state that launched his underdog bid for the White House.

Polls suggest the Illinois senator will win Oregon comfortably while his rival New York Sen. Hillary Clinton is expected to prevail in Kentucky by a wide margin.

But the Obama campaign expects that when the results from the two contests come in, he will have racked up more than halfof the pledged delegates awarded in the state-by-state contests, making him the likely winner in his battle with Clinton to become his party's nominee to face presumptive Republican nominee John McCain in November.

Neither Obama nor Clinton will have enough pledged delegates to lock up the nomination, but Obama contends that superdelegates -- party leaders and elected officials with their own vote in the process -- should back the leader in pledged delegates.

Obama won Iowa's first-in-the-nation nominating contest in January, beating the former first lady who was the national front-runner at the time and was seen by many pundits as having an aura of inevitability in her bid for the Democratic nomination.

Obama's trip to Iowa offers not only a chance for him to look back on the race, but also an opportunity to look ahead to the potential fight with McCain.

Iowa is expected to be an important battleground state in November because its voters in recent presidential elections have been closely divided between Democrats and Republicans.