ABC's George Stephanopoulos reports: Sen. John McCain, R-Ariz., wants to win the election in November. But he does not want to steal Sen. Barack Obama's, D-Ill., thunder this evening, as the Democrat becomes the first African American to accept a major party's nomination for president. A senior McCain campaign official tonight said the news of the Republican's running mate, which is scheduled to be announced tomorow in Dayton, Ohio, will not upstage Obama tonight. "There will be no announcement tonight. There will be no leak tonight. This is Barack Obama's night. His nomination is a singular achievement. Tonight's his night...