(CNN) - Hillary Clinton's campaign says it remains upbeat about the New York senator's White House chances, but rival Barack Obama said Saturday he would likely be treated differently if his campaign had suffered a similar string of losses as her's.
Asked in Ohio by a reporter if he would be treated differently had he lost as many contests as Clinton, Obama said, "Yes."
But Obama said he understands why the treatment is different, saying it would require a knockout blow for Clinton to quit because she's "part of the Democratic network in Washington."
"Look, I'm the challenger, I'm the upstart," he said. "I'm the insurgent - she's, she's the champ. She's part of the Democratic network in Washington and, you know, if you're the title holder then you don't lose it on points. You got to be knocked out."
After essentially tying Obama in the string of states that voted February 5, Clinton has suffered 11 straight losses to the Illinois senator, most recently in the Democrats abroad contest earlier this week.
In a conference call with reporters earlier Saturday, Clinton spokesman Howard Wolfson denied reports some Clinton backers feel Obama has all but locked up the nomination, and said voters in the March 4 primary contests won't base their vote on his string of victories.
"The mood is upbeat, Sen. Clinton is working hard everyday," he said. "Momentum is a media storyline, but that is not an issue on which voters vote."
UPDATE: An earlier version of this report incorrectly stated Obama said he would quit if he had lost as many contests as Clinton.
- CNN's Alexander Mooney