Barack Obama has said Tuesday's primaries in Oregon and Kentucky could mark the end of his drawn-out battle with US Democrat presidential candidate rival Hillary Clinton.
His campaign pressed home that message by announcing a symbolic return to Iowa on Tuesday.
Iowa was the scene of the Illinois senator's first victory in the 2008 presidential nominating race, and his campaign noted it is a critical general election state that Democrats must win in November.
Polls show Barack Obama leading in Oregon, where 52 delegates are up for grabs.
Hillary Clinton is ahead in Kentucky, a state with 51 delegates that has a similar demographic to West Virginia, where she won a thumping victory last Tuesday.
Senator Obama's campaign says he needs just 17 more pledged delegates won through state votes to reach a majority of 1,627, not counting the superdelegates, party officials who can vote either way at August's Democratic national convention.
The official finishing line is 2,025 delegates, including superdelegates.
During a rally in Roseburg, Oregon, yesterday, Senator Obama presented himself as the front-runner almost without question, attacking presumptive Republican nominee John McCain on foreign policy, the environment and healthcare.
