Senator Rand Paul of Kentucky broke Friday with fellow Republicans who have pushed for stricter voting laws as a way to crack down on fraud at the polls, saying that the focus on such measures alienates and insults African-Americans and hurts the party.

“Everybody’s gone completely crazy on this voter ID thing,” Mr. Paul said in an interview. “I think it’s wrong for Republicans to go too crazy on this issue because it’s offending people.”

Mr. Paul becomes the most prominent member of his party — and among the very few — to distance himself from the voting restrictions and the campaign for their passage in states under Republican control, including North Carolina, Ohio and Wisconsin, that can determine presidential elections. Civil rights groups call the laws a transparent effort to depress black turnout.