But Biden, D-Del., said he was most troubled by Alito's comment about reapportionment under the Supreme Court when it was led by Chief Justice Earl Warren.
The Warren Court, as it became known, ended public school segregation and established the election principle of one-man one-vote.
"The part that jeopardizes it (Alito's nomination) more is his quotes in there saying that he had strong disagreement with the Warren Court particularly on reapportionment — one man, one vote," Biden told "Fox News Sunday."
"The fact that he questioned abortion and the idea of quotas is one thing. The fact that he questioned the idea of the legitimacy of the reapportionment decisions of the Warren Court is even something well beyond that," Biden said.
In the document, Alito wrote, "In college, I developed a deep interest in constitutional law, motivated in large part by disagreement with Warren Court decisions, particularly in the areas of criminal procedure, the Establishment Clause and reapportionment," he said.
Biden said the chances of a filibuster against Alito had increased because of Alito's assertions in the document.
"If he really believes that reapportionment is a questionable decision — that is, the idea of Baker v. Carr, one man, one vote — then clearly, clearly, you'll find a lot of people, including me, willing to do whatever they can to keep him off the court. ... That would include a filibuster, if need be," Biden said.
The Supreme Court, in a 6-2 decision in 1962 in Baker v. Carr, ruled that arbitrarily drawn legislative districts can be challenged in federal court.Presumably, the defense of Alito will revolve around "that was 20 years ago, and he was sucking up for a job." What do they think he's doing now?