Obama-Biden ticket ready to debut
NEW: 'Sen. Biden will be a purposeful and dynamic vice president,' Clinton says
Democrat Obama picks Delaware senator as his running mate
Text message announcing Obama's selection goes out early Saturday
Biden to appear with Obama at Springfield, Illinois, rally on Saturday
CHICAGO, Illinois (CNN) -- Thousands of supporters were expected at a Saturday rally in Springfield, Illinois, to see the debut of Sen. Barack Obama and Delaware Sen. Joe Biden as a presidential ticket.
Obama, the presumptive Democratic nominee for president, announced his selection of Biden as his running mate with a 3 a.m. text message and a statement on his official Web site.
"Barack has chosen Senator Joe Biden to be our VP nominee," the text message said.
--MORE With Video--