ST. PAUL — Gov. Sarah Palin of Alaska introduced herself to America before a roaring crowd at the Republican National Convention on Wednesday night as “just your average hockey mom” who was as qualified as the Democratic nominee, Senator Barack Obama, to be president of the United States.

An hour later Senator John McCain, a scrappy, rebellious former prisoner of war in Vietnam whose campaign was resurrected from near-death a year ago, was nominated by the Republican Party to be the 44th president of the United States after asking the cheering delegates, “Do you think we made the right choice” in picking Ms. Palin as the vice-presidential nominee?

The roll-call vote made Mr. McCain, 72, the first Republican presidential candidate to share the ticket with a woman and only the second presidential candidate from a major party to do so, after Walter F. Mondale selected Geraldine A. Ferraro as his running mate for the Democratic ticket in 1984.

But the nomination was a sideshow to the evening’s main event, the speech by the little-known Ms. Palin, who was seeking to wrest back the narrative of her life and redefine herself to the American public after a rocky start that has put Mr. McCain’s closest aides on edge. Ms. Palin’s appearance electrified a convention that has been consumed by questions of whether she was up to the job, as she launched slashing attacks on Mr. Obama’s claims of experience.