Polished and plainspoken, Roberts had been on a likely track to be confirmed as an associate justice and it appeared Bush turned to him for the top job to avoid an acrimonious fight at a volatile moment. Bush was on the defensive about the administration's perceived sluggish response to Hurricane Katrina and his poll ratings had fallen to their lowest point of his presidency.

"The stakes are higher and the Senate's advice and consent responsibility is even more important," said Senate Minority Leader Harry Reid, D-Nev.