Romney said he did call Gingrich after Gingrich won the South Carolina primary earlier in January.

Romney brushed off the lack of acknowledgement by Gingrich. "As has been said long ago, politics ain't beanbags," Romney said on CNN. "We're battling to become the nominee. He's going to do it the way he thinks is best; I'll do it the way I think is best."

Gingrich-supporter Rep. Michael BurgessMichael Clifton BurgessMaternal deaths keep rising in US, raising scrutiny House passes 'right to try' drug bill Overnight Health Care: What to expect in omnibus | HIV expert to head CDC | Sessions issues memo on death penalty for drug cases MORE (R-Texas) argued in a separate interview later on MSNBC that American voters are “not interested in any feud between these two individuals.”

Romney went on to say on CNN that he expected the nomination process would be "a long road." He said on CNN that Gingrich, Santorum and Ron Paul have "the right to stay in the race as long as they want to."

Santorum and Paul moved their campaigns west, leaving Florida to Romney and Gingrich ahead of the state's vote. Both have said they plan to stay in the race as long as they can. Gingrich has argued that the other candidates splitting the conservative vote should drop out of what has become a "two-man race."

"It is now clear that this will be a two-person race between the conservative leader Newt Gingrich and the Massachusetts moderate [Romney]," Gingrich said in his Tuesday-night speech accepting second place in the Florida vote.

--This post was updated at 1:16 p.m.