In an interview to NBC News, Obama said Clinton is quite qualified to be President as also the Vice Presidential candidate.

"If Senator Clinton decides not to go on or if we complete the six contests and we are ahead as we are now. But nothing is certain. I don't want to take it for granted.

"Senator Clinton has been written off before, and came back. And she's a formidable candidate. So obviously we feel good about the results on Tuesday. It strengthens our position. I'm confident that we can finish this, these last few contest, and be in a continuing strong position. It's not yet settled," Obama said.

On the question of considering himself as the ‘presumptive nominee’ of the party, Obama said: "Not yet. I will be".

"That will be an important day. If, at that point, we have the majority of pledged delegates, which is possible, then-- I think we can make a pretty strong claim that—you know, we've got the most wins and it's the ninth inning. And we've won. But do so in a way that brings the party together," Obama said.

This Tuesday, Obama defied opinion polls in North Carolina and trounced Clinton by almost 15 percentage points and lost Indiana by a whisker.

Obama also denied that conversations have taken place between his camp and that of Clinton's on the prospect of the New York Democrat becoming a running mate in his ticket.

"You know we have not had those conversations, because I respect what she has said publicly that she is continuing this campaign.... I want to respect her, and her desire to continue in these coming contests. And as soon as I know I'm the nominee, then I'm going to start making overtures to her, as well as everybody else, to figure out how we can bring this party together," the Illinois senator said.

Although he did not rule out selecting rival Hillary Clinton as his vice presidential running mate if he ultimately defeats her in a race in which he has an almost insurmountable lead.

"There's no doubt that she's qualified to be vice president, there's no doubt she's qualified to be president," Obama told NBC News.

In a CNN interview, he said he had not wrapped up the Democratic presidential nomination, but when he does, he will start going through the process of selecting a running mate.

"She is tireless, she is smart. She is capable. And so obviously she'd be on anybody's short list to be a potential vice presidential candidate," said Obama, who inched closer to winning the nomination by routing Clinton in North Carolina and almost defeating her in Indiana on Tuesday.

Some Democrats are saying Obama and Clinton would be a formidable team against Republican John McCain in the race to the November election.

According to a CBS News/New York Times poll released last week, a majority of both Obama and Clinton voters say they would favor a so-called "Dream Ticket" involving both candidates.