U.S. Republican presidential candidate John McCain has chosen a relatively unknown -- Alaska Governor Sarah Palin -- as his vice presidential running mate.
McCain announced his selection on Friday to a crowd of supporters at a rally in the midwestern city of Dayton, Ohio, ahead of next week's Republican National Convention. He called Palin the "right partner" with strong principles, a fighting spirit and deep compassion.
The social and economic conservative is the first woman to run on the Republican party's national ticket. Democratic candidate Barack Obama has begun a bus tour of key battleground states with his running mate, fellow Senator Joe Biden.
The pair traveled Friday to the eastern state of Pennsylvania where they will be meeting voters and making speeches.
The Gallup polling firm says Obama's lead over his Republican rival grew from a tie to eight percentage points following the four-day Democratic National Convention.