PPP said the 19 points represented Nixon's largest lead since January.
From PPP's analysis:
"Nixon continues to be one of the more popular governors in the country with 54 percent of voters approving of him to 29 percent who disapprove.
"Spence continues to be widely unknown. (Some) 45 percent of voters don't have an opinion about him one way or another. Among those do, 25 percent see him favorably, while 30 percent have a negative view."
PPP said Nixon is winning among independent voters by 54-31 percent and is winning a higher-than-usual share of the GOP vote with 23 percent.
In other races: