Democratic presidential contender Barack Obama forcefully rejected the idea of running as Hillary Clinton's vice presidential running mate Monday. Obama's comments came in the wake of suggestions from the Clinton campaign that the two candidates form a dream ticket, with Clinton in the top spot. VOA National correspondent Jim Malone reports from Washington.

Campaigning in Mississippi in advance of Tuesday's primary, Obama left no doubt that he rejects the idea of joining a ticket in which he would agree to be the vice presidential running mate of Hillary Clinton.

"With all due respect, I have won twice as many states as Senator Clinton," said Obama. "I have won more of the popular vote than Senator Clinton. I have more delegates than Senator Clinton. So, I do not know how somebody who is in second place is offering the vice presidency to the person who is in first place."

Obama's comments came after remarks from Hillary Clinton last week suggesting the possibility of the two rivals running together on the same ticket, with Clinton in the top spot.

"I have had people say, I wish I could vote for both of you," she said. "Well, that might be possible someday."

Clinton's husband, former President Bill Clinton, also promoted the idea, noting that each contender would bring strengths to a combined ticket.

"He would win the urban areas and the upscale voters, and she wins the traditional rural areas that we lost when President Reagan was president," he said. "If you put those two things together, you have an almost unstoppable force."

Clinton and Obama are engaged in a close battle for the Democratic Party's presidential nomination. Obama continues to lead the delegate count by about 100 following his victory Saturday in the Wyoming caucuses.

Obama is favored to do well in the Mississippi primary on Tuesday, while Clinton hopes to regain her momentum with a victory in the Pennsylvania primary on April 22. Opinion polls there give her the lead.

Clinton has questioned whether Obama is ready to serve as president and commander in chief, and that line of attack may have helped her win last week's primaries in Texas and Ohio.

But Obama tried to turn that around Monday by asking why would Clinton want him as her vice presidential running mate if he is not fit to serve as commander in chief?

"Getting all the [retired] generals to say, well, we are not sure he is ready," he said. "I am ready on day one. He may not be ready yet. But I do not understand. If I am not ready, how is it that you think I should be such a great vice president? Do you understand that?"

The Clinton camp had suggested that a combined ticket would be formidable against the presumed Republican nominee, Senator John McCain. But Obama told supporters Monday in Mississippi that Democrats must choose between the two of them for the party nomination.

Political experts believe the idea of a joint ticket, in either combination, could remain viable if the Democratic race remains close right up until the national nominating convention in Denver in late August.

John Fortier is an expert on U.S. politics at the American Enterprise Institute in Washington and a recent guest on VOA's Encounter program.

"The bitterness also will be interesting to watch if we really do come to a very, very close resolution where the candidates feel that they have to come together as a ticket," said Fortier. "It is in some ways unbelievable that they would come together, and yet in other ways it seems almost the way to resolve those differences. And that will be a drama, if it plays out that way, that we will be watching in June or July."

Political rivals have joined forces in the past after bitter presidential campaigns with positive results. Republican candidate Ronald Reagan chose George H.W. Bush as his running mate in 1980, and Democrat John Kennedy did the same in 1960 when he picked Lyndon Johnson as his vice presidential candidate.