I'VE JUST conducted my own presidential poll, but it didn't involve any dialing.

Just driving.

I've informally surveyed several city and suburban neighborhoods with an eye on the yard signs. I'm not prepared to declare a winner, but Barack Obama has a problem in white neighborhoods, or I've just seen the reverse of the Bradley effect on voters' front lawns.

Conventional wisdom is that people lie to pollsters in elections featuring candidates of different races. That's the Bradley effect, named for Tom Bradley, the L.A. mayor once believed to be a shoo-in for California governor. But the polls got that one all wrong. In a black-white race, the theory says, the black candidate polls better than he'll actually do on Election Day.

I saw this firsthand in '87, when Wilson Goode Sr. was forecast to beat Frank Rizzo by double digits but won by only 2 percent. The post-election explanation? White liberals didn't want to tell a pollster they were voting for Rizzo.

This year, some predict a hidden vote for John McCain on the premise that a white voter might be reluctant to tell a pollster he's voting for the Republican lest he be perceived as a racist. The DN's John Baer wrote an excellent column on this on Tuesday.

So what about the yard signs? In the white suburbs of Bucks and Montgomery counties, I've seen a mixed bag. Obama and John McCain are both well-represented, and polls suggest the race there is close. In some neighborhoods, they alternate between lawns, almost like it was planned.

But the city is different. In West Philly, Obama is well-represented, but I couldn't find a McCain sign to save my life - no surprise since Obama is widely believed to be getting 95 percent of the black vote. So the signs match the vote.

In the white wards, it's McCain doing the decorating, and Obama who's scarce.

There are two ways to look at the lack of an Obama presence in white wards: Either he has no support, or residents are reluctant to share that information in a sort of reverse Bradley effect.

In other words, while some voters have been known to untruthfully claim support for a black candidate during a polling call, I suspect others may underreport when it comes to their yard signs. I'm talking white voters willing to vote for Obama, just not anxious to let their neighbors know about their decision.

Don't get me wrong, I expect McCain will do well in the Northeast and South Philly, just not as well as the signs would indicate.

Remember the last two presidential contests: Democrats John Kerry and Al Gore both won 65 percent in the 21st ward, in Manayunk and Roxborough. In the predominantly white Northeast (wards 41, 53-58 and 62-66), Kerry won by an average just shy of 63 percent in 2004, just slightly lower than Gore's take four years earlier.

Sure, those weren't black-white elections. And I know Hillary Clinton soundly defeated Obama in the same wards in April. But you'd think Obama would have more support than is in evidence when you're driving the streets there. Perhaps it's just that some white Obama supporters aren't comfortable advertising that

they're voting for a black man.

Remember, not long ago, a Democratic ward leader from the Northeast told a reporter: "The Dunkin' Donut crowd tells me that we've got everything going for us but Obama."

Why? "It's his color."

THE LEADER of the local ironworkers union confirmed that difficulty. That was the same day an 89-year-old woman at a Frankford Avenue diner told Sen. Biden she wouldn't vote for him:

"Anybody who runs with a guy with a name like that is not going to get my vote. It'd be disgusting to get a man named Barack Obama as president of the United States. No way . . . I'm going to vote for McCain and the lady."

Maybe voters aware of their neighbors' intentions to vote for "McCain and the lady" don't want to let on that they're supporting Obama. So they save the campaign trinkets for inside - not out on the front lawn.

Or they post a McCain-Palin yard sign despite their intentions on Nov. 4.

We'll soon know. There's a reason they put curtains on the voting booths. *

Listen to Michael Smerconish weekdays 5-9 a.m. on the Big Talker, 1210/AM. Read him Sundays in the Inquirer. Contact him via the Web at www.mastalk.com.