One concern some liberals have is over Kagan's position on affirmative action. It's unclear what it is, but Kagan did not have a particularly good record of hiring women or minorities while serving as dean of Harvard's law school.

Under her watch, the school hired 29 new professors. All except one were white, and only six were women. A Duke University professor pointed out the track record, prompting the White House to respond that Kagan did put black and Latino candidates in the running for positions, even if they weren't ultimately selected.

If major civil rights groups are upset, they haven't let it show yet. A National Association for the Advancement of Colored People official backed Kagan when she was nominated as solicitor general, saying she transformed the law school into a more diverse place in other ways.

The issue could actually play in the president's favor. Justice Sonia Sotomayor was criticized from the right over the perception that she was too supportive of affirmative action, so a critique from the left this time around that Kagan is not supportive enough offsets that.

The Republican Party has tried to fight back by implying that Kagan favors affirmative action. They found an article she wrote about Justice Thurgood Marshall, for whom she clerked, in which she discusses Marshall's desire "to protect the people who were unprotected by every other organ of government."

"Does Kagan still believe that the Supreme Court's primary mission is to 'show a special solicitude for the despised and disadvantaged?'" the Republican memo asks, quoting Kagan from the 1993 piece .

-- Ambreen Ali, Congress.org