Rudy Giuliani is among the Republicans in Denver making their case against Barack Obama.

He's doing that by pointing out that Joe Biden made quite a turn around from his position during the primaries, that Obama is not prepared to be president.

"Joe Biden, his running mate... has quite often made the point that Barak Obama is unprepared to lead," Giuliani said. "These are not the usual issues that exist between candidates."

Giuliani says that none of McCain's opponents questioned his readiness to lead during the Republican primaries, but that a number of Democrats had raised that concern about Obama.