From a May 10 New York Times article:

The criticism, though, was not echoed by several leading Republican lawyers, who voiced their support for Ms. [Elena] Kagan.

“I would think that the president is looking for a bona fide left-of-center candidate with a progressive personal outlook who is a rigorous lawyer -- and he hit pay dirt,” said Miguel Estrada, who was nominated to a federal appeals court by President George W. Bush but was never confirmed. “She's highly capable and should be confirmed.”

Estrada had previously expressed his support for Kagan's nomination as solicitor general. He's just one of numerous Republicans who have expressed their support for Kagan, among them Charles Fried, Kenneth Starr, and Theodore Olson, who served as solicitors general in Republican administrations.