Painting himself as an outsider who would reform Washington, Romney vowed to battle to the White House.
"It's time for politicians to leave Washington and for we, the people, to take over," the former Massachusetts governor and multimillionaire businessman told hundreds of cheering supporters in a convention center ballroom here. "This isn't just about the heart and soul of our party; it isn't just about which party's going to win in November. It's about the future of our country."
Romney's strategists said that they never expected to receive a majority of delegates Tuesday and that they were counting on a strong showing in Western states such as California, Colorado, and North Dakota, which remained too close to call by the time Romney and his family left the convention center to head home to Belmont, Mass.
"The West has always been our hope," said Al Cardenas, chairman of Romney's Florida effort.
"Coming in, we knew that Sen. [John] McCain was going to do real well in the Northeast, except of course Massachusetts, where we did real well. We knew it would be a tough contest in the South with Gov. [Mike] Huckabee doing well. We thought our strength was in the West, and sure enough."
Even as supporters at the convention center saw the vast majority of states go to Romney's rivals, they appeared to remain upbeat.
Dan Avila, 50, a lawyer from Everett, Mass., expressed confidence that Romney would continue the race and be a formidable candidate.
"You're looking at a very well-organized and well-funded candidate who has a sense of public service," he said. "He's not going to quit."