Washington (CNN) - Has Herman Cain joined Rick Perry and Mitt Romney in what's described as the top tier of candidates in the race for the Republican presidential nomination?
That's what a new Fox News national poll seems to suggest.
The survey, released Wednesday, indicates that 17 percent of likely GOP primary voters say they back Cain, a businessman, former Godfather's Pizza CEO, and radio talk show host, for their party's presidential nomination. According to the poll, Cain is just two points behind Texas Governor Rick Perry (at 19 percent) and trails former Massachusetts Gov. Mitt Romney (at 23 percent) by six points. Both of those differences are within the poll's sampling error.
Cain has jumped 11 points from the last Fox poll, which was conducted in late August. The new survey was conducted Sunday through Tuesday, after last Thursday's GOP presidential debate, and also after Cain's overwhelming victory Saturday at a much watched straw poll of Florida Republican activists.
Perry has dropped ten points since the last Fox poll, and for the first time in a month the Texas governor isn't on top of the field in a major national GOP survey. The poll was conducted after Perry's uneven performance at that most recent presidential debate, and after Perry's distant second place finish at the Florida straw poll. Analysts and pundits had expected Perry to capture that non-binding vote.
Romney's numbers have stayed basically the same from August to late September, according to the Fox poll, and his four point advantage over Perry is within the poll's sampling error. Former House Speaker Newt Gingrich did gain support in the Fox poll, moving from 3 percent in the late August poll to 11 percent in the current poll.
The Fox poll comes days after the release of a CNN/ORC International poll which also indicated gains for Gingrich and Cain in the wake of last Thursday's debate but still had Perry at the top of the GOP list. Without former Alaska Governor Sarah Palin in the race, the CNN poll, conducted in the three days immediately following the debate, showed Perry at 30 percent, Romney at 22 percent, Gingrich at 11 percent, and Cain at 9 percent.
Both surveys indicate a long-term drop for Rep. Michele Bachmann of Minnesota, whose standing in national polls has plummeted since winning a crucial straw poll in Iowa on August 13. Bachmann is at three percent in the new Fox poll and at four percent in the CNN survey.
"A lesson we have to re-learn every cycle is that the 'top tier' and every other tier is not made of concrete, but of Silly Putty," says Rich Galen, a Republican strategist who advised former Senator Fred Thompson during his 2008 GOP presidential bid. He is the author of Mullings.com, an online column.
"Former Minnesota Gov. Tim Pawlenty and Rep. Michele Bachmann were once in the 'top tier' but Ron Paul has never been. Perry entered the race in the top tier, but who knows if he will stay there. If Herman Cain is in the top tier we'll have to see how long it lasts. Might end up with him accepting the nomination next August; might end up with him dropping out in December," adds Galen.
The Fox News Poll was conducted September 25-27, with 925 registered voters nationwide, including 363 GOP primary voters, questioned by telephone. The survey's overall sampling error is plus or minus three percentage points, with a sampling error of plus or minus five percentage points for questions asked only to GOP primary voters.
– Follow Paul Steinhauser on Twitter: @PsteinhauserCNN