Newt Gingrich has hit out at fellow Republican presidential candidate Mitt Romney as someone who cannot bring enough change to Washington.
Speaking after a fourth place finish in the Iowa caucuses, Mr Gingrich said his rival is a nice man - but incapable of doing what is necessary to fix the country.
He also criticised Mr Romney for running a negative campaign.
Mr Gingrich shrugged off his Iowa disappointment, and said the race for the GOP nomination is just beginning. He vowed to go on, and insisted he is the candidate to create change.
Mr Gingrich congratulated two other contenders - Rick Santorum and Ron Paul - but said he will air contrasts between himself and Mr Romney.
Meanwhile, fellow candidate Rick Perry said he will now reassess his White House bid after coming fifth in Iowa.
He said he will return home to Texas to determine whether there is a path forward for his campaign.
Earlier in the day, Mr Perry had encouraged supporters to keep the faith as his advisers looked ahead to South Carolina as the first real test of his presidential campaign.