With voters standing in line at polling places around the country, many people didn't need a nudge.
"I'm stoked. This is a historic event," said Andrew Lind, a 28-year-old underwriter from Ventura, Calif., who wore a green Obama T-shirt.
Obama, accompanied by his wife and two daughters, turned in his ballot at his Chicago neighborhood precinct-"I voted," he told reporters, holding up a validation slip-and then headed to neighboring Indiana for a last-minute speech designed to prompt as many Democrats and independents as possible to vote in the Republican swing state.
"The journey ends," Obama told reporters, "but voting with my daughters, that was a big deal."
In Phoenix, McCain left his high-rise condominium to cast a ballot at a nearby church before preparing to fly to Colorado and New Mexico, two battleground states he would likely need to score an upset victory. He gave supporters a thumbs-up sign and was in and out of the polling place within minutes.
"Nobody knows what the voter turnout's going to be," McCain told "Good Morning America" on ABC in an interview hours before polls opened. "I'm very happy with where we are. We always do best when I'm a bit of an underdog."
The running mates were voting, too. Democrat Joe Biden gave a thumbs-up after casting a ballot near his hometown of Wilmington, Del., his mother, wife and daughter at his side. He turned to his 91-year-old mother and joked, "Don't tell them who you voted for."
Republican Sarah Palin arrived overnight in Anchorage, Alaska, to drive up to her tiny hometown of Wasilla to vote before returning to the airport for a flight to Phoenix to join McCain. She cast her ballot in the town's council chamber, where she had presided as Wasilla's mayor.
"Here in Alaska, where we've cleaned up the corruption and we've taken on some self-dealing and self-interests, we've been able to really put government back on the side of the people," Palin told reporters after voting. "I hope, pray, believe I'll be able to do that as vice president for everybody in America, helping to transform our national government, too."
Although the path to an Electoral College triumph appeared narrow for McCain-polls showed Obama with an advantage in many of the battleground states they have contested in the campaign's final weeks-the Arizona senator remained hopeful for a surprise victory.
"I think these battleground states have now closed up, almost all of them, and I believe there's a good scenario where we can win," McCain told CBS' "The Early Show" in an interview broadcast Tuesday.
Obama campaign manager David Plouffe said he was confident that new voters and young voters would fuel an enormous turnout to benefit the Illinois senator.
"We just want to make sure people turn out," Plouffe told "Today" on NBC. "We think we have enough votes around the country."
Sen. Hillary Rodham Clinton, who lost the nomination to Obama in a bitter primary battle but campaigned for him after he received the Democratic nomination, voted with her husband, the former president, near their home in upstate New York. She told reporters, "I feel very good about what's going to happen today."
Waiting in line at polling places, voters appeared determined to have their moment after watching from the sidelines since the candidates were nominated by their parties more than two months ago.
"Either way it goes, we're either going to have the first female vice president or the first African-American president, and I think that's historic and wonderful that we are getting more diverse," said Danielle Ury, 27, who stood outside Cleveland's Pilgrim United Church of Christ.
At Herndon High School in northern Virginia, 51-year-old Jennifer Howard had huddled under an umbrella with a handful of others to be among the first to vote. "I knew the lines were going to be really long," she said.
Nedra Pickler reported from Chicago and Beth Fouhy from Phoenix. Associated Press writer Michael Blood reported from Wasilla, Alaska.