ANKENY, Iowa — At a recent ice cream social here, Jim Hallihan liked what he heard from Senator Marco Rubio.

He praised the Florida senator’s youthful optimism and his eloquent testimony to the opportunities America offered.

But there was something larger that drew Mr. Hallihan, a former Iowa State basketball coach, to Mr. Rubio, 43, the son of poor Cuban immigrants.

“The day of the older white guy is kind of out,” said Mr. Hallihan, a 70-year-old white guy.

As Mr. Rubio has introduced himself to curious, and overwhelmingly Caucasian, Republican audiences from Iowa to New Hampshire, he has vaulted to the front ranks of the early pack of likely presidential candidates, partly because of his natural political talent. But it may owe just as much to the combination of his personal story and the balm it offers to a party that has been repeatedly scalded by accusations of prejudice.