Though former Massachusetts Gov. Mitt Romney has a commanding lead in the crucial race for delegates, Santorum said the race is about to enter a period where he will face fewer disadvantages. To date, Romney has outspent Santorum and had stronger campaign organizations working for him.
"They are not going to nominate a moderate Massachusetts governor who's been outspending his opponent 10-1 and can't win the election outright," Santorum said on NBC's "Today" show. "What chance do we have in a general election if he can't, with an overwhelming money advantage, be able to deliver any kind of knockout blow to other candidates?"
"We're going to be the nominee," Santorum said, adding later, "Gov. Romney will not make it."
It will take 1,144 delegates to win the GOP nomination when the party holds in convention in Tampa in late August. According to a count by The Associated Press, Romney has 454 delegates and Santorum has 217, compared with 107 for former House Speaker Newt Gingrich and 47 for Texas Rep. Ron Paul.
"We're closing the deal, state by state, delegate by delegate," Romney said on Fox News' "Fox and Friends" Monday. He said that though some states award delegates based on the proportion of votes they receive, lengthening the process, "We're winning this and I expect we're going to get the nomination."
Alabama and Mississippi hold their presidential primaries on Tuesday.
Romney's campaign plus an allied campaign committee run by former Romney aides is spending over $2.5 million on television ads in the two states. Santorum's campaign has few commercials there, though a separate campaign committee that supports him is spending around $500,000 on advertising.