It seems that Senator Barack Obama thought that a Supreme Court nominee who had not been a judge would need to take time to illustrate her views on various constitutional issues facing the country.
Greg Sargent provides the Nexising and the emphasis:
Harriet Miers has had a distinguished career as a lawyer, but since her experience does not include serving as a judge, we have yet to know her views on many of the critical constitutional issues facing our country today. In the coming weeks, we’ll need as much information and forthright testimony from Ms. Miers as possible so that the U.S. Senate can make an educated and informed decision on her nomination to the Supreme Court.
Except for the obvious difference in having had what Obama called "a distinguished career as a lawyer" his 2005 call for explication of her views certainly can be applied to his nominee to the Court, Elena Kagan.