The top Republican in the Senate demanded assurances on Wednesday that President Barack Obama's solicitor general and friend, Elena Kagan, would be free of White House influence if confirmed as a Supreme Court justice.

"Americans want to know that Ms. Kagan will be independent," Minority Leader Mitch McConnell said in a Senate speech as Obama's Supreme Court pick began a series of courtesy visits with senators who will decide whether to confirm her.

McConnell noted that when Obama nominated Kagan to the Supreme Court on Monday, he said that "they're friends."

"It's my hope that the Obama administration doesn't think the ideal Supreme Court nominee is someone who would rubber stamp its policies," McConnell said. "But this nomination does raise the question. And it's a question that needs to be answered."

For the past year, Kagan, 50, has been Obama's solicitor general, a post in which she argues cases on behalf of the U.S. government before the Supreme Court. She is widely expected to be approved for a seat on the high court by the Democratic-led Senate before lawmakers' August recess.

Yet with Republicans' conservative base fired up for the November congressional election, McConnell and other Republicans are expected to subject her to tough scrutiny.

Kagan is seen as a moderate, and much of Obama's largely liberal base had been pushing for a more liberal nominee.