Former Minnesota Gov. Tim Pawlenty, meanwhile, announced his candidacy in a video Sunday night and said he plans to begin his campaign with a speech in Iowa on Monday
But many Republican activists don't find the new clarity satisfying.
The Daniels decision to skip a White House bid has turned the attention of uncommitted Republican donors and activists to those candidates who actually are in the race, and some prominent Republicans said Sunday that donors who had been waiting for Mr. Daniels' decision will likely move into the Pawlenty camp.
But Mr. Daniels' announcement also immediately increased the clamoring in some GOP quarters for other candidates to enter the race. New Jersey Gov. Chris Christie, Texas Gov. Rick Perry and former Alaska governor and vice presidential nominee Sarah Palin are all being urged by various GOP factions to run, though the prospects of any of them choosing to do so didn't appear strong.
In the wake of Mr. Daniels' announcement, advisers to Gov. Christie remained adamant that he isn't interested.
Rep. Ron Paul also will pursue the nomination, and he has strong supporters among Republicans with libertarian leanings.
On Saturday, Mr. Cain, the former chief executive of Godfather's Pizza and head of the restaurant industry's largest trade group, drew thousands to an Atlanta amphitheater to hear his official announcement.