Voters will have to decide whether they will embrace what Mr. Paul acknowledges are “tough choices” — like his proposals to raise the age of Social Security eligibility, to slash spending deeply enough to balance the budget every year even while cutting taxes and relying more on charity to provide the social services that the government has since the New Deal…

And his campaign is a microcosm of the unlikely, and sometimes contradictory, mashup that created the Tea Party movement, one that brings together idealistic and largely young supporters who espouse the small-government ideas of the Austrian economic school and public choice theory, with largely older voters who fervently want change in Washington but who also think big government programs like Social Security and Medicare are worth the costs…

Voting in the Republican primary in Mr. Paul’s precinct here, Martha McKenzie, 84, said Mr. Paul was too idealistic. “He says things, and I wish they could be that way, but I know they’re not,” she said. “I don’t mind paying taxes. Not when it’s to help people. We didn’t get this way in a few years, we’re not going to get out of it in a few years. You can’t cut things all of a sudden, not without hurting people.”

Her niece Donna Wolbe, 57, said she worries about what she called Mr. Paul’s “my-way-or-the-highway” politics. “You want to feel like the person you’re voting for is going to be effective,” she said. “You’re not effective if you alienate people.”