According to the St. Louis Business Journal, John McCain has expanded his lead over Barack Obama in Missouri, a new survey says. The survey in question is an automated poll conducted over four days by Public Policy Polling, a firm out of Raleigh, North Carolina.

McCain’s advantage is 50-40, a seven-point increase from Public Policy Polling’s July poll, which showed him leading by three points.

Obama’s biggest issue is with white voters, who support McCain by a 56-35 margin, observers say.

“There aren’t enough black voters in Missouri for Barack Obama to win it if he can’t make things more competitive among white voters,” said Dean Debnam, president of Public Policy Polling, in a statement. “That’s going to be his challenge if he wants to have any chance at winning the state.”

McCain leads across every age group and has the advantage with both men and women, the poll shows.

In the gubernatorial race, according to the poll, Democrat Jay Nixon leads Republican Kenny Hulshof 48-42. In other statewide races, Lt. Gov. Peter Kinder and Secretary of State Robin Carnahan hold double-digit leads, while in the open seats for attorney general and treasurer, Democrat Chris Koster and Republican Brad Lager each hold a narrow advantage.

In the 2010 race for the U.S. senate, it appears both Russ Carnahan and Dick Gephardt could give Kit Bond “a run for his money” if they chose to seek the seat, the pollster said. Bond leads Carnahan 46-43 and Gephardt just 44-43 in hypothetical match-ups. PPP showed a total of 750 likely voters were surveyed from Aug. 13-17.

Click here to see Public Policy Polling’s info packet.