Sen. McCain has chosen his running mate and the person will be notified on Thursday, a senior campaign official said.

    A friend said McCain had pretty much settled on his selection early this week, and it crystallized in the past few days. Campaign manager Rick Davis flew to McCain's cabin in Sedona, Ariz., a few days ago to confer, and another meeting about the choice was held with top aides Wednesday.

    The news leaked on the third night of the Democratic National Convention, detracting attention from speeches by former President Bill Clinton and the Democratic ticket mate, Sen. Joe Biden of Delaware.

    McCain's selection process has been conducted mostly in secret, but officials said he was considering one or more candidates who support abortion rights. The disclosure set off a fracas on the right wing, with talk-show host Rush Limbaugh saying such a selection would destroy the party.

    McCain is planning to roll out his vice presidential nominee in three battleground states this weekend, with large-scale rallies planned for Ohio, Pennsylvania and Missouri, according to aides and advisers.

    The GOP nominee-in-waiting will move to immediately change the campaign conversation from Barack Obama's football stadium acceptance speech Thursday to the new Republican ticket, to be revealed at a noontime Friday rally in a Dayton, Ohio, basketball arena. McCain and his running mate will then travel by bus to Pennsylvania, where they'll hold an outdoor event at a minor league baseball stadium in Washington County, just southwest of Pittsburgh. On Sunday, the duo will head to suburban St. Louis for another event to be held at a minor league baseball stadium, this one in O'Fallon, Mo.

    The Missouri rally is being billed to local Republicans as something of a unity rally, since it will feature McCain, Mitt Romney and Mike Huckabee - the GOP presidential finalists who effectively divided the vote three ways in the Show Me State's Super Tuesday primary. A McCain aide warned not to read too much into McCain's planned guests, however.

    The campaign's leadership has imposed a strict rule on staffers to not discuss the process and have further guarded the selection by parceling out very little information.

    Speculation is increasingly centered on former Massachusetts Gov. Mitt Romney and Minnesota Gov. Tim Pawlenty, although Connecticut Sen. Joe Lieberman remains an option and is in the final mix.