Democratic presidential candidate Barack Obama reached into the deep pockets of his campaign to air a 30-minute prime-time pitch on U.S. networks Wednesday night, in a slick infomercial largely aimed at the working class.

Republican candidate John McCain, after choosing to only accept public donations for the campaign, has been outspent nearly two-to-one by Obama.

The infomercial began at 8 p.m. ET on NBC, MSNBC, CBS, FOX, Univision, BET and TV One, and ended with a live appearance by Obama at a Florida rally.

"America, the time for change has come," he told supporters.

"To all of you, and all of those who joined us from across the country: in six days, we can choose an economy that creates jobs and fuels prosperity, starting with the middle class; in six days, we can choose to invest in healthcare for our families, education for our kids and renewable energy for our future; in six days, we can choose hope over fear."

The infomercial was in the style of a documentary and told the stories of various American families struggling in the current economic turbulence. Obama narrated the show himself.

Not since Ross Perot in 1992 has a presidential candidate financed such an infomercial during primetime.

It's believed Obama's campaign spent US$3 million to air the infomercial, which McCain called an excessive amount of money. McCain also complained the broadcast would delay Wednesday's World Series baseball game by 15 minutes, although that appeared unlikely.

"No one will delay the World Series with an infomercial when I'm president," he joked while campaigning in Pennsylvania, home of the Philadelphia Phillies, the potential champion.

McCain also fought back by unleashing a 30-second attack ad that dismissed the infomercial as a "TV special" with more style than substance.

"Behind the fancy speeches, grand promises and TV special, lies the truth," an announcer says. "With crises at home and abroad, Barack Obama lacks the experience America needs. And it shows. His response to our economic crisis is to spend and tax our economy deeper into recession. The fact is Barack Obama's not ready yet."

An analysis of the upcoming election by The Associated Press has concluded that Obama is headed toward victory. He is leading in enough states to win the necessary 270 electoral votes, with several states to spare.

"Even if McCain sweeps the six states that are too close to call, he still seemingly won't have enough votes to prevail, according to the analysis, which is based on polls, the candidates' TV spending patterns and interviews with Democratic and Republican strategists," the report says.

But Obama has taken pains to tell supporters that the race is not over, and that he needs to carry his momentum into voting day on Nov. 4.

At the Florida rally that followed his infomercial Wednesday night, he asked voters to "stand with me and fight by my side" to secure the White House.

Obama, Clinton share stage for first time

Later in the evening, Obama joined former president Bill Clinton at another Florida rally in Orlando. It was the first time the two men had shared the same stage.

During the Democratic nomination race, when Obama was engaged in a fierce campaign against Clinton's wife, Sen. Hillary Clinton, the former president had dismissed Obama's potential nomination as a "fairytale."

But late Wednesday, Clinton smiled and clutched Obama's hand as he told supporters the young senator represented America's future.

The Republicans won Florida in the last election, but Clinton encouraged voters to support Obama as they had supported him during his own successful run at the White House.

"It's time to come back again, so we can take America forward," he said.

Obama also appeared Wednesday on The Daily Show, which airs on CTV and the Comedy Network in Canada. On Thursday, his media blitz will continue with interviews on NBC's "Nightly News" and "The Rachel Maddow Show" on MSNBC.