WASHINGTON (AFP) - Sonia Sotomayor, nominated by President Barack Obama Tuesday as the first Hispanic Supreme Court justice, worked her way from low-income New York City housing to the polished federal courtroom.

The 54-year-old Puerto Rican jurist represents the president's first attempt to shape the high court for a generation, filling the vacancy of retiring Justice David Souter.

Supreme Court expert Tom Goldstein said nominating Sotomayor, who was born to a Puerto Rican family in the Bronx, New York, and could become the third woman to sit on the top US court, was "an absolutely historic landmark" for Hispanics.

Her nomination delighted Latino voters, the fastest-growing demographic bloc in the United States and one that helped power Obama's 2008 election win.

It also put a political squeeze on any Republicans plotting to thwart her Senate confirmation process, which is rxpected to begin by July.

Sotomayor's remarkable rise in some ways mirrors that of Obama, having overcome humble origins as a minority child to reach the pinnacle of US public life.

"She's faced down barriers, overcome the odds and lived out the American dream," Obama said Tuesday.

Divorced with no children, and with a reputation as a workaholic, Sotomayor often speaks of the courts as "the last refuge for the oppressed."

"I strive never to forget the real world consequences of my decisions on individuals, businesses and government," she told reporters Tuesday.

"She has never forgotten where she began, never lost touch with the community that supported her," Obama said, adding that it was key that a justice know "how the world works, and how ordinary people live."

That quality of empathy, which the president had said was essential for his pick, makes Sotomayor stand out in contrast to Souter, who plans to return to his beloved home state of New Hampshire after 19 years on the bench.

"She has been in a more difficult financial situation than most of the justices, and someone who clearly had to work hard for everything she got. She has a prospective there that others don't," American University law professor Amanda Frost told AFP.

Sotomayor, however, would likely not shift the balance of power on the Supreme Court. Although Souter was appointed by a Republican president - George H.W. Bush - he became part of the court's liberal wing.

"It does little to change the balance of the court," commented Leslie Sanchez, a former aide to Obama's predecessor, George W. Bush.

"She would not change the vote on the major questions, on the major controversial issues," added Frost, while noting that Sotomayor "does bring a different perspective and background that may influence the court."

Sotomayor, who has served for more than a decade on a federal appeals court in New York, is "a prudent, careful liberal, respectful of Supreme Court precedent but willing to push its limits to defend the rights of the individual," legal analyst Jeffrey Toobin said on The New Yorker's website.

Although Sotomayor suffers from Type-1 diabetes, which can lower life expectancy by 7 to 10 years, Obama aides said they were confident she was in "good health."

For more than a decade, Sotomayor has been mentioned by Democrats as a possible future Supreme Court appointment.

But she has been in sights of Republicans, who see her as a proponent of "hard-left" values, and have targeted her rulings as inimical to conservative causes.

"Judge Sotomayor is a liberal judicial activist of the first order who thinks her own personal political agenda is more important than the law as written," said the conservative Judicial Network.

She has also drawn critics for telling a legal seminar that a "court of appeals are where policy is made," which conservatives see as a sign of legislating from the bench.