Saturday's Gallup tracking poll revealed two big numbers for Obama. Obama hit 50% in the tracking poll and took an 8% lead over McCain. This isn't the first time that Obama has hit the 50% mark, and it isn't the first time he has held a lead of 8%; but now we are in the last month of the campaign and numbers like these in October usually mean electoral success in November.
Using Gallup's compendium of presidential trial heat polling since 1936, I counted16 candidates who received 50% support or higher in an October Gallup poll. Hitting the 50% mark was a very good predictor of victory. Of those 16 candidates, just two failed to win the general election--Al Gore and Thomas Dewey.
An 8% lead has also been difficult for trailing candidates to overcome. Only one candidate who held a lead of at least 8% in October ended up losing the election--once again, that was Al Gore in 2000. There were thirteen other occasions since 1936 where a candidate had an 8% lead or greater in at least one October poll, and in each case that candidate won.
While the history doesn't look good for Republicans, the McCain campaign can take some solace from 2000. In that campaign, Gore's support reached as high as 51% (and he had a 10% lead over Bush) early in October. However, he quickly lost that lead after the first debate and Bush actually built his own 13% lead in a late October Gallup poll. This was the only time that both candidates reached 50% and held a lead of at least 8% in October Gallup polls--yet another way in which the 2000 election was truly unique. The McCain campaign will have to hope they can duplicate Bush's 2000 comeback rather than go on to defeat like the other 13 candidates who found themselves behind by 8% in October.
NOTE: Mark Blumenthal emailed to point out that the 2000 Gallup tracking poll was highly volatile in 2000 and it may be the case that this volatility was at least partly responsible for both Gore and Bush hitting 50% (and for both taking 8% leads) during October that year.