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In trying to expand the Republican coalition, Mr. Paul is fighting political and demographic trends that are pushing more voters away from his party. A new generation is less socially conservative on issues like same-sex marriage, and a growing minority population is increasingly Democratic.

His campaign, which he is expected to announce early next month, will be a test of whether the kind of Republican rebranding he is attempting can happen in the next year, or whether it will take much longer, if it happens at all.

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"It's not always easy," Mr. Paul said in an interview here. He insisted that the political operation he is building is aimed at 2016, not some later date. But he acknowledged that he is not expecting instant results.

"Unless you are somehow this miraculous faith healer," he said, "it's going to be a gradual thing in the sense that people will open up to considering you. But most of them are saying things like: 'We're happy that you're competing for our vote. We're happy to see you coming where Republicans haven't come before.'"

"If we don't let it happen," he added, "I think we're not going to win national elections again."

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At South by Southwest, that approach drew curious spectators like Charlie Maas, who works in advertising and was visiting from Los Angeles. "I saw Rand Paul on the schedule and said: 'Huh. I'd go to that. That's interesting.'"

Interesting is the adjective so often used to describe Mr. Paul. The other word that many people often use after hearing him speak is "but" as in they were happy to listen to him, but they were not yet convinced that they could vote for him.

"It's one thing to be interesting; it's another thing to be compelling," said Matthew Dowd, who was a top strategist for George W. Bush. "They've got to see him sitting in the Oval Office. And I do not think Rand has crossed that threshold yet."

Excerpt from:
Rand Paul captures a new audience