Palin's experience — she has been mayor of tiny Wasilla, Alaska, and has served as the state's governor for less than two years — has been questioned since McCain chose her last week. The process that led to her selection has been criticized as hasty because McCain had met her just once before he offered her the job.

Palin also is the subject of an ethics investigation involving the firing of the state's public safety commissioner after he wouldn't dismiss her former brother-in-law, a state trooper. Her efforts as mayor to gain millions of dollars in federal funding through the so-called "earmark" process appeared to be at odds with the McCain message of fiscal reform.

Her personal life became a topic of discussion after Palin revealed that her daughter was pregnant. Yet her candidacy has excited Republicans at the convention and across the country, in part because she has earned a reputation for taking on entrenched interests in Alaska and is staunchly pro-gun and anti-abortion.

"Give her a chance to make her first speech, give her a chance to do her first interview," said former New York Mayor Rudy Giuliani, the convention's keynote speaker.

"Of course it's going to be high stakes," Giuliani said in an interview Wednesday with "Good Morning America" on ABC. "The media is ready to pounce on any mistake. ... She looks to me like she's got tremendous confidence, got tremendous ability as a speaker."

Palin walked onto the spare stage at the Xcel Center about 6:20 a.m. local time for a run-through and spent about 10 minutes looking out into the nearly empty arena and discussing where she would stand at the lectern and where she would look during her prime-time speech. Joining Palin were McCain campaign manager Davis and senior adviser Nicolle Wallace.

The disclosure Monday that Palin's daughter Bristol is five months pregnant — and a continuing drip of potentially embarrassing details — knocked the convention off message before a rousing program Tuesday night.

Speakers extolled McCain as a war hero and maverick senator while blasting Democrat Obama as an untested liberal. The 47-year-old Illinois senator is seeking to become the first black president.

"Democrats present a history-making nominee for president. History-making in that he is the most liberal, most inexperienced nominee ever to run for president," former Tennessee Sen. Fred Thompson said as delegates roared with delight.

Palin, who has been in St. Paul since Sunday but out of sight, has a chance Wednesday to speak above the media din and present herself directly to voters as a strong-willed reformer and a solid conservative with appeal to women, including supporters of failed Democratic candidate Hillary Rodham Clinton.