Liu, a professor at Berkeley School of Law, testified at Alito's Judiciary Committee confirmation hearing, telling senators that Alito's judicial record showed "a uniform pattern of excusing errors and eroding norms of basic fairness."
Lee, a member of the Judiciary Committee, took particular umbrage at Liu's written testimony where he argued that Alito's judicial record envisioned a country where police could use deadly force in minor crimes and the FBI could secretly put cameras in bedrooms.
"His comments about Justice Alito were offensive not simply because they were unhelpful in his confirmation process but because they were a misleading and unwarranted personal attack on a dedicated public servant," said Lee, who served as law clerk for Alito at the appellate level and once he joined the Supreme Court in 2006.
The Senate voted 52-43 on Thursday to block Liu's nomination to the 9th Circuit Court of Appeals. Sen. Lisa Murkowski, R-Alaska, was the only Republican who voted to move Liu's nomination forward, while Sen. Ben Nelson, D-Neb., was the lone Democrat to oppose it. It would have taken 60 votes to avoid a filibuster and reach a final Senate vote.
Minority Leader Mitch McConnell, R-Ky., called some of Liu's views "repugnant."
"What do Mr. Liu's writings reveal? Put simply, they reveal a left-wing ideologue who views the role of a judge not as that of an impartial arbiter, but as someone who views the bench as a position of power," McConnell said.
Sen. Orrin Hatch, a former Judiciary chairman, was the only senator to vote "present" on Thursday. He refuses to vote to block a nomination from going forward but didn't want his vote misconstrued as supporting Liu's nomination.
Hatch spoke on the Senate floor Thursday.
"In article after article, in speech after speech, he argues that judges on this quest for new constitutional meaning may find it in such things as the concerns, conditions and evolving norms of society; social movements and practices; and shifting cultural understandings," Hatch said. "No matter how you cut it, these are simply alternative ways of saying that the Constitution means whatever judges say it means."
Democrats, such as Judiciary Chairman Patrick Leahy, defended Liu as a talented attorney who "reveres the Constitution."
"No one can question the man's intellect or qualifications," he said. "Nothing I have read or heard from Professor Liu gives me any reason to doubt his conviction about the critical importance of the rule of law as the guiding principle of judicial decision-making."
Leahy also told reporters before the vote that should Liu be filibustered, it would fully reignite the battles over the federal bench and would assure that Democrats would do the same to the next Republican president's nominees.
The Washington Post contributed to this story