Mike Allen cites sources saying the Arizonan plans to spend his 72nd birthday naming his running mate at a huge 10,000-person rally in Ohio.
The announcement would come early in the morning August 29, the day after Obama accepts his party's nomination at Invesco Field.
He would later appear with his No. 2 at a large-scale event in Pennsylvania.
Friends emphasize he talks about the decision with almost no one, could even change the announcement plans and go sooner.
