Former Fla. Gov. Jeb Bush, whose endorsement would be a prize for any of the Republican presidential candidates, has remained neutral.
This follows a pattern in early GOP contests: Gov. Terry Branstad in Iowa didn't choose sides. Nor did influential Sen. Jim DeMint in South Carolina.
New Jersey's Gov. Chris Christie threw his support to Romney, but there hasn't been a delegate-selection contest yet in New Jersey.
The New York Times reported in Monday's editions that Romney has sought to win over Jeb Bush, a brother of former President George W. Bush.
Asked about that in a Fox News Channel interview on Monday morning, Romney replied: "Jeb Bush and I haven't spoken. He's a good man. I'd love to get his opinion on any number of issues."