Leading candidates to join the McCain ticket appear to be either former Massachusetts Gov. Mitt Romney and Minnesota Gov. Tim Pawlenty. But sources say Connecticut Sen. Joe Lieberman, a political independent and abortion rights supporter, is still a long-shot possible choice, Politico reported Wednesday.

Regardless, the vice presidential candidate will join McCain. R-Ariz., on a whirlwind campaign tour designed to immediately offset Democratic candidate Barack Obama's Thursday night acceptance speech. The Republican ticket will be unveiled at noon Friday Dayton, Ohio, followed by a bus trip to Pennsylvania. On Sunday the pair will head to suburban St. Louis for an event being billed as a unity rally, because participants will include McCain, Romney and former Arkansas Gov. Mike Huckabee, Politico said. The three were the leading GOP presidential vote-getters in Missouri's presidential preference primary.

A McCain aide, however, warned Politico not to read too much into McCain's planned guests.