Gregory Korte

USA TODAY

WASHINGTON — President Obama has come to regret his decade-old filibuster of Justice Samuel Alito, the White House said Wednesday as Senate Republicans threatened to block his nominee to replace Antonin Scalia on the Supreme Court.

The Alito nomination has become one of many historical footnotes that have taken on new relevance as Obama and the Republican-controlled Senate jockey for high ground in their battle over the election-year Supreme Court nomination. White House Press Secretary Josh Earnest called Obama's decision to join in the filibuster of Alito in 2006 a "symbolic vote" based on specific objections to Alito's rulings as a lower court judge.

"What the president regrets is that Senate Democrats didn't focus more on making an effective public case about those substantive objections," Earnest said. "Instead, some Democrats engaged in a process of throwing sand in the gears of the confirmation process. And that's an approach that the president regrets."

At the time, Obama told ABC News that he supported the filibuster "because I think Judge Alito, in fact, is somebody who is contrary to core American values, not just liberal values." Obama said the court needed to "provide some check on the executive branch, and he has not shown himself willing to do that repeatedly."

But during his nomination of Sonia Sotomayor in 2009, now-President Obama already appeared to have misgivings, saying "last-minute efforts using procedural maneuvers inside the Beltway, I think, has been the wrong way of going about it."

And at a news conference on Tuesday, Obama said both parties bear some responsibility for the broken nomination process.

"I think what’s fair to say is that how judicial nominations have evolved over time is not historically the fault of any single party. This has become just one more extension of politics," he said. "What is also true is Justice Alito is on the bench right now."

Alito was confirmed by a vote of 58 to 42, one week after his confirmation cleared the Judiciary Committee.

10 years after, Supreme Court Justice Samuel Alito makes his case

Obama also acknowledged a well-known secret of legislating: The opposition party often allows some senators to vote against a nominee, while also counting votes to ensure the confirmation goes forward. "And my expectation is, is that the same should happen here," Obama said Tuesday.

The issue of Obama's 2006 opposition to Bush's last Supreme Court nominee has re-emerged in the wake of Obama's intent to nominate a justice to replace the conservative Scalia. Senate Majority Leader Mitch McConnell has suggested that the Senate won't even consider any nomination, saying it should be left to the next president to decide.

"There is a difference between the president's symbolic vote against President Bush's Supreme Court nominee and Republicans' reflexive opposition to the idea of President Obama even nominating anybody to the Supreme Court," Earnest said. "What Republicans are advocating is wrong and is inconsistent with the requirements of the Constitution, primarily because the wording of the Constitution is unambiguous and does not provide an exception for election years."

It's unclear how long it will take for Obama to put forward a name. Previous vacancies have taken about a month, although Obama already has a short list from his two previous nominations and appears anxious to move quickly once Scalia's funeral is over and the Senate returns from recess next week.

Obama to visit Supreme Court Friday to pay respects to Scalia

The White House would not rule in or out any candidate for the nomination, except one: Obama himself.

"The president himself has said in the past that, while he obviously holds in high esteem those who dedicate their lives to serving the country on the Supreme Court, he envisions something different for himself once he leaves the presidency," Earnest said. "So I haven't asked him that direct question, but I think all the available evidence indicates that that option is highly unlikely."