It’s well clear from the month of August’s nationwide pre-election “Obama versus McCain opinion polls” that Sen. Barack Obama is leading nationally in his presidential race with Sen. John McCain.

Obama leads McCain in all the national opinion polls conducted in August, except two polls; one conducted by Reuters/Zogby (August 14-16) and the other by Gallup Daily Tracking (August 23-25).

Here’s the detail of what the month of August’s “McCain vs Obama opinion polls” say —

(UPDATE) Gallup Daily Tracking’s Obama McCain Opinion Poll, conducted from August 27 to August 29, showed Obama leading McCain by 8% points — 49% to 41% among the registered voters nationally.

Gallup Daily Tracking’s Obama McCain Opinion Poll, conducted from August 26 to August 28, showed Obama leading McCain by 8% points — 49% to 41% among the registered voters nationally.

Rasmussen Reports Tracking’s Obama McCain Opinion Poll, conducted from August 26 to August 28, showed Obama leading McCain by 4% points — 49% to 45% among the registered voters nationally.

Gallup Daily Tracking’s Obama McCain Opinion Poll, conducted from August 25 to August 27, showed Obama leading McCain by 6% points — 48% to 42% among the registered voters nationally.

Gallup Daily Tracking’s McCain Obama Opinion Poll, conducted from August 23 to August 25, showed McCain leading Obama by 2% points — 46% to 44% among the registered voters nationally.

Zogby Interactive’s Obama McCain Opinion Poll, conducted from August 23 to August 24, showed Obama leading McCain by 3% points — 45% to 42% among the registered voters nationally.

USA Today/Gallup’s Obama McCain Opinion Poll, conducted from August 21 to August 23, showed Obama leading McCain by 4% points — 47% to 43% among the registered voters nationally.

ABC News/Washington Post’s Obama McCain Opinion Poll, conducted from August 19 to August 22, showed Obama leading McCain by 6% points — 49% to 43% among the registered voters nationally.

FOX News’ Obama McCain Opinion Poll, conducted from August 19 to August 20, showed Obama leading McCain by 3% points — 42% to 39% among the registered voters nationally.

YouGov/Econcomist’s Obama McCain Opinion Poll, conducted from August 18 to August 20, showed Obama leading McCain by 1% point — 39% to 38% among the registered voters nationally.

CBS News/NY Times’ McCain Obama Opinion Poll, conducted from August 15 to August 19, showed Obama leading McCain by 3% points — 45% to 42% among the registered voters nationally.

NBC News/Wall Street Journal’s McCain Obama Opinion Poll, conducted from August 15 to August 18, showed Obama leading McCain by 3% points — 45% to 42% among the registered voters nationally.

Rasmussen Reports Tracking’s Obama McCain Opinion Poll, conducted on 16 August, showed Obama leading McCain by 1% point — 46% to 45% among the registered voters nationally.

Reuters/Zogby’s McCain Obama Opinion Poll, conducted from August 14 to August 16, showed McCain leading Obama by 5% points — 46% to 41% among the registered voters nationally.