After bouncing back from defeats last week to claim an easy victory in Wyoming at the weekend, Obama said: "You won't see me as a vice presidential candidate. I'm running for president. We have won twice as many states as Senator Clinton, and have a higher popular vote, and I think we can maintain our delegate count." he Telegraph quoted Obama as saying that he remained focussed on winning the Democratic nomination and changing the country
Hillary Clinton has repeatedly hinted that Obama could join her on her ticket as a way of ending the current impasse over the nomination.
Obama, 46, has a virtually unbeatable lead of about 150 pledged delegates to represent him at August's party convention.
That leaves Mrs Clinton relying on the unlikely possibility of most of the 796 party leaders, known as "super-delegates" going against the wishes of Democratic voters.
Clinton also hopes to overtake Mr Obama's 600,000 lead in the total popular vote among Democrats.
This would be hard to achieve with just 11 contests left, though the New York senator would be helped if there were a re-run of voting in Florida and Michigan.
Meanwhile, former U.S. President Bill Clinton has suggested that a joint Hillary Clinton-Barack Obama ticket would be "almost unstoppable".
"Look at most of these places," the ex-President said while on the stump for his wife in Mississippi. Obama would win the urban areas and the upscale voters, and she wins the traditional rural areas that we lost when President Reagan was President. If you put those two things together, you'd have an almost unstoppable force," he claimed.
As the rivals look ahead to delegate-heavy Pennsylvania's April contest, a new Newsweek poll shows that Clinton's March 4 wins have helped her obliterate Obama's national lead among Democrats.
Obama leads the New York senator 45% to 44% - a statistical tie - among party members in the new poll. By comparison, a late February CBS/New York Times survey had Obama 16 points ahead.
Some 69 percent of Democrats now love the idea of a combined "Dream Team" ticket, according to Newsweek - "leaving aside the crucial question of who runs on top."