PRINCETON, NJ -- Rick Perry's image is suffering, with his Positive Intensity Score among Republicans familiar with him down to 15, and below 20 for the first time. Meanwhile, Herman Cain's score is now 30, the highest for any candidate this year.

The results are based on Gallup Daily tracking from Sept. 19-Oct. 2. Gallup calculates candidate Positive Intensity Scores as the percentage of strongly favorable opinions minus the percentage of strongly unfavorable opinions of each candidate among Republicans and Republican leaners familiar with the candidate.

The movement in Perry's and Cain's scores follows recent campaign developments, including poor reviews of Perry's performance in the September debates and Cain's surprising win in the Sept. 24 Florida straw poll.

In addition to Perry, Michele Bachmann and Ron Paul established new low Positive Intensity Scores this week, at 5 and 3, respectively. Bachmann was among the highest-rated candidates in June, peaking at 24, but has seen a steady decline since she posted a score of 20 in Aug. 1-14 tracking. Paul has not been rated as positively, with a high of 16 in May, and has registered in the single digits in all but one update since late May.

The net result of the changes is that Cain has established a wide advantage over any other Republican candidate in Positive Intensity Scores, with Perry (15), Mitt Romney (13), and Newt Gingrich (11) well behind Cain's 30. Rudy Giuliani (19) and Sarah Palin (13), whom Gallup tracks but who have not made decisions regarding entering the race, would also trail Cain by a considerable margin. The remaining announced candidates -- Rick Santorum (8), Bachmann (5), Paul (3), and Jon Huntsman (-1) -- have much less positive images among Republicans familiar with them.

Cain's very positive image is offset by his lower name recognition, though he has become better known in recent weeks, with 55% of Republicans now familiar with him. He still trails the five best-known candidates -- Bachmann, Gingrich, Perry, Romney, and Paul, all near 80% recognition. Santorum (54%) and Huntsman (43%) are less well-known.

Implications

Cain's straw poll win, and his resulting gains in recognition and positive intensity, may have made him a legitimate contender for the Republican nomination in Republicans' eyes. Despite his positive image throughout the campaign, Cain typically fared poorly in Republican nomination preference polls, but recent polls by other polling organizations suggest he is now more competitive with front-runners Romney and Perry. Gallup will report an update on nomination preferences early next week.

A candidate needs high name recognition in order to be a factor in the nomination contests. Along with increased familiarity comes increased scrutiny of the candidate and his or her record. Also, when candidates appear to be legitimate contenders, their opponents begin to attack their records on the campaign trail and in the debates. These dynamics appear to have played out for Bachmann and Perry, who saw their healthy Positive Intensity Scores decline as they became better known, though Perry remains among the front-runners.

Thus, Cain will have to weather the next few debates and the next few weeks of campaigning if he is to solidify a position as a leading contender for the nomination.