PITTSBURGH -- Despite Sen.Barack Obama's lead in the polls, Massachusetts Gov. Deval Patrick said you can't always trust the numbers.

Patrick made several stops on Monday in Pittsburgh, including the Homewood Senior Center, to rally up support for Obama.

So far Obama is leading in the polls over Republican presidential candidate Sen. John McCain. But Patrick said as history has shown, that can change come Election Day.

"I hate polls. I wish we didn't have to have them. But if we have them I'd rather they be close. It's very important that people not let up and (keep) working up until the very end," said Patrick.

Polls don't always indicate who wins, especially in an election with an African-American candidate. Take the 1982 California gubernatorial race, when former Los Angeles mayor Tom Bradley, an African-American, lost the election despite leading his white opponent in the polls. Political analysts call it the "Bradley Effect;" where white voters say they intend to vote for a black candidate but don't come Election Day.

"I worry that they are suggestive. I worry that polls showing Sen. Obama ahead means people will let their guard down and stop working," Patrick said.

Patrick said that's why he believes the only numbers to count are those on Nov. 4th.

"It's the result of all of you and me and everybody else going out and doing their civic duty and casting their vote," Patrick said.

Patrick returns to Massachusetts on Tuesday, but will be back on the campaign trial again next weekend.