Barring extraordinary circumstances, Solicitor General Elena Kagan should win confirmation to the Supreme Court on the strength of Democrats' numerical advantage in the Senate.

To stop her from becoming the nation's 112th justice, Democrats would have to abandon President Barack Obama and his second high court pick or almost all of the GOP senators would have to agree to filibuster the nomination _ more than a year after seven of them voted for Kagan to become the solicitor general.

It is unlikely that Republicans will try to block her, said Manuel Miranda, chairman of the conservative Third Branch Conference.

"She shouldn't be filibustered, she won't be filibustered," said Miranda, a former Senate staffer who worked on judicial nominations. "Probably no nominee would have been filibustered. The notion of a filibuster is a distraction. The real issue becomes how heavily she'll be scrutinized and how great an investment in time will Republicans invest. The next level of investment is not a filibuster, but how much effort Republicans will devote to this nomination."

Obama announced Kagan as his second pick to the nation's highest court on Monday. If confirmed, she would join Justices Ruth Bader Ginsburg and Sonia Sotomayor in bringing the number of women on the Supreme Court to three, the highest in the court's history.

Women already represent 31 percent of all sitting justices on state Supreme Courts, according to the National Center for State Courts.

Kagan's nomination "represents a historic step forward as women continue to take their rightful place on the highest court in the land," said Nan Aron, leader of the liberal Alliance for Justice.

The Senate will determine whether the 50-year-old Kagan will become the replacement for retiring Justice John Paul Stevens. Democrats control the chamber with 59 votes, one short of what they would need to forestall any possibility of a partisan filibuster.

Senate Judiciary Chairman Patrick Leahy, D-Vt., said Kagan's confirmation will likely come before August.

"The decisions made at the nation's highest court affect the daily lives of all Americans," Leahy said. "Our constituents deserve a civil and thoughtful debate on this nomination, followed by an up-or-down vote."

Kagan will immediately begin courting the votes she needs by calling on members of the Senate, including leaders like Republican Leader Mitch McConnell of Kentucky.

McConnell said "Senate Republicans will treat Ms. Kagan fairly."

"We will carefully review her brief litigation experience, as well as her judgment and her career in academia, both as a professor and as an administrator," McConnell said. "Fulfilling our duty to advise and consent on a nomination to this office requires a thorough process, not a rush to judgment."

Seven Republicans have already voted once for Kagan, when her nomination came before the Senate last year to become the solicitor general. That means it's unlikely they will be able to unify to block her from the Supreme Court.

"Her previous confirmation, and my support for her in that position, do not by themselves establish either her qualifications for the Supreme Court or my obligation to support her," said Sen. Orrin Hatch, R-Utah, and member of the Senate Judiciary Committee. "I have an open mind and look forward to actively participating in the confirmation process."

Carrie Severino, chief counsel and policy director of the conservative Judicial Crisis Network, said she doesn't think Republicans will attempt a filibuster. "I think if her nomination goes down, it will be because the moderate Democrats don't want to vote for a controversial nominee, so I don't think it'll come to a filibuster," she said.

Not all Democrat-affiliated groups are happy with Obama's choice. Some are concerned that replacing Stevens _ the leader of the court's liberal bloc _ with a moderate like Kagan would have the net effect of making the court more conservative.

"If the president's nomination of Elena Kagan is successful, the result will move the Supreme Court to the right. Progressives should fight the Kagan nomination," said Norman Solomon, progressive activist and author of "War Made Easy: How Presidents and Pundits Keep Spinning Us to Death."

Glenn Greenwald _ a columnist for online magazine Salon.com and author of "How Would a Patriot Act?" _ called Kagan a "blank slate, institution-loyal, seemingly principle-free careerist." But he also said progressives will not successfully oppose her.

"In reality, no matter what they know about her and, more to the point, don't know, they'll support her because she's now Obama's choice, which means, by definition, that she's a good addition to the Supreme Court," Greenwald said. "Our politics is nothing if not tribal, and the duty of every good Democrat is now to favor Kagan's confirmation."

The solicitor general _ known informally as the "tenth justice" _ represents the United States, including defending acts of Congress, at the Supreme Court and deciding when to appeal lower court decisions.

Kagan has never been a judge. Beyond her work as solicitor general and her time as dean of Harvard Law School, she does not have much material her opponents can use to attempt to forestall her confirmation.

"While I opposed Ms. Kagan's previous nomination to be solicitor general, I look forward to carefully reviewing her qualifications and record from throughout her career," said Sen. John Thune, R-S.D. "... Given that Ms. Kagan does not have a judicial record, it will be especially important for senators to inquire as to her views on the Constitution and the role of the court."