McCain spotlighted Palin at the suburban St. Louis rally - giving her the clean-up speaking spot on a stage erected over the ballfield's home plate. She got an enthusiastic reception from the crowd that filled the infield bleachers and spread from the dirt base paths into the outfield grass. At various times, they chanted, "Sarah, Sarah."
The ball team's president said the stadium holds about 15,000 for such concert-style events. McCain's campaign estimated there were 23,000 people.
The rally was held on important political ground for McCain in his November matchup against Democrat Barack Obama. O'Fallon is located in St. Charles County, a traditional Republican base.
In each of the past two elections, President Bush was spurred to victory in Missouri partly because his combined votes from St. Charles County and from the southwest Missouri Republican stronghold of Greene County more than made up for his deficit in the state's most populous area of St. Louis County.
Palin, a 44-year-old mother of five and a first-term governor, carries strong social conservative credentials that often prove important in those areas. She was raised in a Pentecostal church, is a member of the National Rifle Association and has calls herself "as pro-life as any candidate can be."
"She's fantastic!" exclaimed Jody Garcia, 48, of nearby Belleville, Ill. "She's smart, she's young, she's energetic, she's has all the right stances on issues," namely on abortion and guns.
"I would have been supporting McCain anyway, but now I'm excited," Garcia added.
Missouri Lt. Gov. Peter Kinder proclaimed that McCain has "supercharged" his campaign with the selection of Palin. "Before, the attitude of folks on our side was, 'Well, we're going to vote for McCain, but we're not enthusiastic,' and the question of how much we're going to go out and work was in doubt," Kinder said in an interview. Now, "our coalition is reassembled as a fighting army."
McCain and Palin flew into St. Louis on Saturday night. But before the rally, they jetted to Mississippi to tour an emergency management center bracing for Hurricane Gustav. They used the Missouri event to urge residents along the Gulf Coast to evacuate.
McCain also used it as a sort of formal introduction of Palin to Missourians.
"When you get to know her, you're going to be as impressed as I am. She's got grit, integrity, good sense," McCain said.
Palin cast herself as a reformer, proclaiming that as governor, "I have stood up to the old politics as usual and the special interests and the lobbyists and Big Oil and to the good ol' boy network."
Democratic U.S. Sen. Claire McCaskill, a close ally of Obama's, criticized Palin as a "risky" vice presidential pick during a news conference earlier Sunday in St. Louis.
"It shows he is perfectly willing to abandon the modern middle and wrap himself around the radical right in this country," McCaskill said.
While McCain's event showcased Democrats who are supporting him Sunday, Obama's campaign said it planned to launch a "Missouri Republicans for Obama" effort on Monday. Obama's campaign said later that it had postponed the event because of developments related to the hurricane.
At McCain's rally, Republicans were encouraged to wear red to the stadium - a color that happens to belong to the St. Louis Cardinals but, in this case, was intended to demonstrate their desire to keep Missouri a red Republican state instead of letting it slip to Democratic blue.
As part of the build up to McCain's speech, the crowd heard from Sen. Kit Bond, Gov. Matt Blunt, former Sen. Jim Talent, Republican gubernatorial candidate Kenny Hulshof and Republican 9th District congressional candidate Blaine Luetkemeyer.
After an opening act from another country music band, singer John Rich crooned a special McCain song and delivered an unconventional endorsement to rousing applause. To bolster a claim that McCain - a former prisoner of war in Vietnam - should be popular among young people, Rich declared him to be "one of the most bad-ass men that ever walked the face of the earth."
