Kerry Spot at NRO has the most recent Gallup poll numbers. If they're accurate they aren't good news for the Kerry campaign. They show Bush moving ahead 50 - 47 among likely voters.
Bush has several tactical advantages going into the next several months and one possible pitfall (at least the Dems will see it that way. It's not clear that it really is a pitfall). Bush has the release of the book Unfit For Command coming up next week, he has the convention in about two weeks from which he will probably derive a modest boost, and he has a lot of ad material on Kerry that makes Kerry look very indecisive, even silly. If Bush does reasonably well in the debates he'll be holding all the cards. Kerry has no ammo left to shoot. He'll be on the defensive about his military fictions for the next month or so and will find it hard to regain the offensive momentum that he had coming out of his convention.
If Iraq continues to move toward stability and democracy, if oil prices moderate, and if there is no national emergency, three big but not improbable "ifs", Kerry will be bereft of a major issue.
His only hope for persuading the electorate to switch horses is a big win in the debates. He shouldn't be over-confident, however. Gore and his supporters thought he would wipe the floor with Bush in the 2000 debates, but it didn't work out that way. Bush has been fortunate in his opponents who seem almost psychologically unable to resist the temptation to "misunderestimate" him.