Herman Cain may still be a longshot in the race for the Republican presidential nomination, but he's coming on strong. Rick Perry seemed to be a lock, but his GOP star is falling fast.

Cain is busy promoting his new book, This is Herman Cain! My Journey to the White House which arrived at retailers this week and is most certainly headed to bestsellers lists.

Currently on Amazon's bestseller's list, Cain's new book is ranked #9 among all books, and it has sold out of immediate stock. Also, inventory at book wholesalers, including Ingram, is moving fast, according to Nielsen Bookscan, which tracks industry activity.

Meanwhile, Perry, the Texas governor, is raising lots of money for his presidential run -- a reported $17 million through Sept. 30 -- But it's not helping him fend off rising Republican contender Herman Cain.

Perry's fundraising is likely more than his competitors, including Cain, have raised in the latest reporting quarter in the bid to earn the Republican party's presidential nomination, and it speaks to six weeks of forward momentum he had since entering the race on Aug. 13.

Disclosures are due on Oct. 15, but Perry's campaign revealed its latest totals on its Web site Wednesday. Perry's figure is less that Republican contender Mitt Romney, the former Massachusetts governor, raised in the second quarter before Perry entered the race but its also likely the most any will report for the latest period.

But that's not been enough for Perry to fend off the rising political star of Cain. The former Godfather's Pizza CEO is fast gaining momentum in the Republican presidential race, and is starting to make a run for it after his Florida straw poll victory.

Cain has never held elected office, but his common sense, experienced business tone delivered with a Baptist preacher's flair is beginning to resonate with many voters, according to a new ABC News/Washington Post poll.

Perry, who's been at or near the top of most polls since announcing his bid for the GOP nomination two months ago, is slipping. The new poll shows Perry has lost roughly half of his support over the past month.

And as Perry slips down, Cain, from Georgia, is on the rise. The ABC News/Washington Post poll showed Cain is now tied for second place, with Perry, after Mitt Romney.

Perry's slip is attributed to several factors, including a subpar showing in several recent debates and opposition to his immigration policies in Texas. Meanwhile, Cain's star has been rising with potential voters who see him as effectively articulating solutions to America's ailing economy, including his 9-9-9 tax plan.

Under his 9-9-9 plan, Cain proposes a 9 percent corporate tax, a 9 percent personal income tax and a 9 percent national sales tax. He believes the plan is simple enough to promote economic growth.

From the Washington Post: Rick Perry's star in the race for the GOP presidential nomination has faded, as most of those tuning in to recent debates say the more they hear about the Texas governor, the less they like him. By contrast, Herman Cain appears to have benefited, moving into the top tier.

The new poll revealed that among the nearly half of Republicans and GOP-leaning independents who said they've watched recent debates, 70 percent like Cain more, while only 29 percent like Perry more. Some 56 percent said the more they see of Perry, the less they like of him, while only 12 percent said the more they see of Cain they less they like of him.

When asked If the 2012 Republican presidential primary or caucus in your state were held today, for whom would you vote? Perry slipped from 29 percent in September to 16 percent now. Cain improved from four percent in September to 16 percent now -- tied with Perry.

Romney, the former Massachusetts governor, moved back into the lead in the poll, at 25 percent. Romney had led in July, but slipped to second behind Perry in the poll in September.

That can only mean one thing for Perry: He's in trouble despite the strong fund-raising.

Cain's consistent and reverberating voice gains traction when he gets before people. Perry goes in the other direction after he gets in front of people. But Perry came out strong because he had money out of the gate. Cain, meanwhile, started slowly, with little money and visibility.

Cain changed all that in the Florida straw poll, however, inspiring delegates in a speech that changed the contest in an instant.

Cain won the Florida straw poll, and he has since won the hearts and minds of many conservative American voters. Look for that trend to continue, as Cain gets more exposure and raises more money. Cain has Perry on the run, while he's headed in the opposite direction.