The three national tracking polls that were published on Friday all moved toward President Obama, probably reflecting momentum from the Democratic convention.

In the Gallup national tracking poll, Mr. Obama moved into a three-point lead over Mitt Romney, up from one point on Thursday.

What’s a bit more worrisome for Mr. Romney is that Gallup’s reporting of the head-to-head results in its poll occurs over a lengthy seven-day window, meaning that only a minority of the interviews in the poll were conducted after the major speeches at the Democratic convention. In fact, most of the interviews in the poll were conducted just after the Republican convention in Tampa, Fla., a period in which Mr. Romney should have been enjoying a convention bounce of his own. Read more