Washington (CNN) - Former presidential candidate Republican Steve Forbes predicted Mitt Romney will "limp over the finish line" to capture the GOP presidential nomination in a fight that will not end in the next few months.
Forbes, the editor-in-chief of Forbes Media who previously backed Rick Perry for president, said in an interview broadcast Sunday that Rick Santorum's recent ascendancy in the race will contribute to the extended battle.
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"Santorum, I think, is going to have a good week and on Tuesday," Forbes said on CNN's "State of the Union" in reference to upcoming contests. "And so I don't think it's going to be a knockout blow anytime soon. So I see this going right into June."
On the same program, former Democratic House Majority Leader Richard Gephardt, who also ran for president, said Romney is more likely than Santorum to present a strong message on the economy in the fall.
"To do well in the presidential campaign, they've got to have a strong economic message, and to the extent that Rick Santorum has been talking more about social issues and less emphasis on the economic issues, it may be that Romney could fulfill that role better," Gephardt told CNN Chief Political Correspondent Candy Crowley.
However, Gephardt said a lack of a dominant Republican presidential candidate makes it increasingly likely the Senate will remain in Democratic control.
Forbes and Gephardt each mounted two unsuccessful runs for their party's presidential nomination – Forbes in 1996 and 2000 and Gephardt in 1988 and 2004.
Gephardt, who represented Missouri in the House for almost three decades, said super PACs have changed the viability of presidential campaigns.
"When you ran out of money, you couldn't buy an airplane ticket to go to the next stop. So that's when people usually got out. So that's what happened to me in my races," Gephardt said. "But that may be a little changed today."
Despite the presence of super PACs, Forbes said at some point the candidates still lose credibility.
That point will come on Tuesday for Newt Gingrich, Forbes said, when voters in the southern states of Alabama and Mississippi cast ballots.
"If he doesn't do well or carry both of those, he's just not going to have the credibility. He can carry on, but he's not going to be taken seriously as a possible winner," Forbes said.
Santorum and Gingrich have received calls to drop out of the race despite capturing delegates and states early in the nominating cycle. To date, Romney has won the most delegates.
Gephardt said the decision to suspend a campaign is ultimately organic.
"When you can't make payroll, it's obvious that you need to get out, because you don't want to hurt these people and you can't really ask them to be volunteers for month after month when you can't pay payroll," Gephardt said. "So your campaign manager, you know, you're talking every day, every minute of every day and so you pretty easily come to the decision that's right.”
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