Stamford, Connecticut (CNN) - Former New Hampshire Gov. John H. Sununu will endorse Mitt Romney on Monday, Sununu confirmed to CNN.
Republicans in the state had widely expected the New Hampshire Republican wise man to support Romney. His endorsement is highly prized and provides another sign the GOP establishment is backing Romney, a former Massachusetts governor, in the race for the presidential nomination. Sununu, who served as chief of staff to George H.W. Bush, will also serve as chairman of Gov. Romney's national steering committee, the campaign said.
New Hampshire is the first state to hold a primary, and helps set the tone for the race. It is the nation's second nominating contest after the Iowa caucuses.
Sununu's move comes after a difficult week for Romney in New Hampshire, after he was faulted by some for campaigning in Nevada despite a tussle with New Hampshire.
After intense pressure from Republican officials, Nevada voted Saturday to push back its caucus date, leaving New Hampshire second after Iowa.
Romney will file his paperwork for candidacy in the New Hampshire primary Monday morning, his campaign said.
The Sununu endorsement was first reported in the New Hampshire Union Leader.