from CNN
"Possible replacements include Attorney General Alberto R. Gonzales and federal courts of appeals judges J. Michael Luttig, John Roberts, Samuel A. Alito Jr., Michael McConnell, Emilio Garza and James Harvie Wilkinson III. Others mentioned are former Solicitor General Theodore Olson, lawyer Miguel Estrada and former deputy attorney general Larry Thompson, but Bush's pick could be a surprise choice not well known in legal circles"
Hmmm, looks like there are lots to choose from. I think Gonzales is too contraversial for the timeframe in which they have to get the nominee aprroved, so I expect it will be one of the others listed here.