(CNN) -- Sen. Barack Obama flatly rejected suggestions Monday he would be a vice presidential running mate for Sen. Hillary Clinton.
Sen. Barack Obama speaks to supporters during a rally in Columbus, Mississippi, Monday.
Clinton, Obama's rival for the Democratic presidential nomination, and her husband, former President Clinton, have suggested a joint Clinton-Obama ticket -- with Obama in the second slot.
President Clinton Saturday suggested a Clinton-Obama ticket would be "unstoppable."
"He would win the urban areas and the upscale voters. She would win the rural areas that we lost when President Reagan was president," he said while campaigning in Pass Christian, Mississippi. "If you put those two things together, you'd have an almost unstoppable force." Watch Bill Clinton tout a 'dream ticket' »
Obama forcefully shot that idea down.
"Sen. Clinton is fighting hard. She's tenacious. I respect her for that. She is working hard to win the nomination. But I want everybody to be absolutely clear. I'm not running for vice president. I'm running for president of the United States of America," Obama told supporters during a rally in Columbus, Mississippi.
If anyone should be suggesting vice presidential candidates, it should be him, Obama said.
"With all due respect. I won twice as many states as Sen. Clinton. I've won more of the popular vote than Sen. Clinton. I have more delegates than Sen. Clinton. So, I don't know how somebody who's in second place is offering vice presidency to the person who's in first place," he said. Watch Obama downplay talk of 'dream ticket' »
Obama also said the Clinton campaign was "hoodwinking" voters when it suggested he was not ready to be president while also floating the possibility of a joint Clinton-Obama ticket.
"I don't understand," he said. "If I'm not ready, how is it that you think I should be such a great vice president?"
Obama was campaigning in Mississippi a day before the state holds its primary Tuesday, while Clinton keeps her eye on the next big prize on the Democratic calendar, Pennsylvania.
Thirty-three delegates are at stake Tuesday, and in the tight Democratic race, every delegate is critical. CNN estimates Obama leads Clinton 1,553 to 1,438. A candidate needs 2,025 delegates to win the nomination.
Obama won the Wyoming caucuses Saturday, where he picked up seven delegates. Clinton won five delegates.
Obama was also scheduled to hold a rally in Jackson, Mississippi, Monday, while Clinton was set to hold campaign events in Scranton, Pennsylvania. Pennsylvania holds its primary April 22.
The divergent paths on their campaign trails may be a reflection of what the campaigns view as their political strengths.
Obama has done well in Southern states that have large African-American populations. Clinton has done better in industrial states with large groups of blue-collar voters such as Ohio, which she won last week. Watch why black voters are flocking to the polls »
Going into Tuesday's voting, Obama has a double-digit lead over Clinton in Mississippi, polls suggested. An American Research Group poll conducted March 5-6 of likely primary voters had Obama leading Clinton 58 percent to 34 percent with 5 percent supporting another candidate and 3 percent unsure. The poll's margin of error is plus or minus 4 percentage points. Watch an Obama aide explain why Obama will not be a VP candidate »
Clinton has not conceded the state to Obama, however. She campaigned there last week, and her husband campaigned there over the weekend. Watch how Hurricane Katrina is shaping Tuesday's election »
As the race has remained in a virtual deadlock, pressure has been mounting on party officials to find a solution that lets Michigan and Florida have some input in the nomination process.
Both states were stripped of their delegates by the national Democratic Party after they violated party rules and moved their primaries to January. Clinton won both contests.
None of the top-tier candidates campaigned in either state before the votes, and Obama was not on the ballot in Michigan.
How the question is resolved could have a significant impact on the Democratic race. Florida has 210 delegates, while Michigan has 156 delegates.
Ann Lewis, a senior Clinton adviser, argued the outcome of Florida's January primary should be used to allocate Florida's delegates. Watch Lewis explain why the Florida results should count
"Here's what we think the criteria should be: Recognize and respect the fact so many Florida Democrats did come out," Lewis said. "Let's remember and recognize the people who did show up and appreciate that they thought votes should be counted."
But comments by Howard Dean, the chairman of the Democratic National Committee, suggested party leaders would not support that position.
"I think it's very unlikely that Florida and Michigan, given how close this race is, are going to be seated as is," Dean told CBS Sunday. "But everybody's going to work very hard to find a compromise within the rules that's fair to both campaigns that will allow Florida and Michigan in the end to be seated."
Sen. Bill Nelson, D-Florida, has proposed Florida Democrats get a chance to vote again using mail-in ballot, saying a full primary using regular voting machines would be prohibitively expensive.
Nelson estimated the cost of conducting an election using mail-in ballots would be about $6 million. Florida's Democratic Party would raise the money to pay for the mail-in election, he said.
Two prominent Democratic fundraisers -- Gov. Ed Rendell of Pennsylvania and Gov. John Corzine of New Jersey -- suggested they would be willing to help raise the funds necessary to hold new elections in Florida and Michigan.
A letter outlining their proposal was published Sunday in the Washington Post. Rendell and Corzine said they would help raise half of the $30 million they estimated it would take to hold primaries in Florida and Michigan.
Both Rendell and Corzine back Clinton, but former Sen. Tom Daschle, Obama's campaign co-chairman, said the Obama campaign would be open to the two campaigns raising funds for new primaries. E-mail to a friend