Obama introduces running mate Biden to nation

SPRINGFIELD, Illinois (CNN) - Presumptive Democratic presidential nominee Barack Obama introduced his newly selected running mate to the nation on Saturday, telling supporters that Sen. Joe Biden is "a leader who is ready to step in and be president."

"For months, I've search for a leader to finish this journey alongside me and join me in making Washington work for the American people. I searched for a leader who understood the rising costs confronting working people and will always put their dreams first," Obama said. "Today, I've come back to Springfield to tell you I've found that leader."

The rally is the pair's first joint appearance since that Obama announced Biden would be his running mate on his Web site and in a text message to supporters early Saturday morning.