Polls aren't elections

Public opinion polls show Barack Obama and John McCain tied or separated by tiny margins.
That's bad news for Obama. If the past is prologue, he will need a fairly wide lead in the polls to win the upcoming presidential election.
There are reports that Obama campaigners think he has to lead by 5 to 8 percentage points to prevail.
Their obstacle is the "Bradley effect," named after Tom Bradley, longtime Democratic mayor of Los Angeles who ran for governnor in 1982. The polls had Bradley, who is black, up by 10 points leading up to the election, but he lost to Republican George Deukmejian, who is white.
Why? No one has figured it out exactly, but the answer lies in the tangled nature of race relations.
One theory holds that white voters are reluctant to tell pollsters they intend to vote against a black candidate, even though that's what they subsequently do.
The discrepancy between poll numbers and election reslults has become known as "the Bradley effect, but it also has been known as "the Wilder effect" and other names because the pattern has popped up time and again.
Whatever the root cause, black candidates do better in polls than in elections.
Now, for the first time, one of the candidates for president is black. Will the Bradley Effect come into play?
Why not? Thugs have threatened violence if Obama loses, one even predicting a race war.
That would seem to give voters more incentive than ever before to conceal their opposition to Obama.
In Minnesota, ordinarily blue, Obama is barely ahead, and closet supporters of McCain-Palin could easily tip the state into the red column. Several other states are in similar situations.