Here are reactions from lawmakers, party leaders and organizations.
President Barack Obama
"Over a distinguished career that spans three decades, Judge Sotomayor has worked at almost every level of our judicial system, providing her with a depth of experience and a breadth of perspective that will be invaluable as a Supreme Court justice.
"It's a measure of her qualities and her qualifications that Judge Sotomayor was nominated to the U.S. District Court by a Republican President, George H.W. Bush, and promoted to the Federal Court of Appeals by a Democrat, Bill Clinton. Walking in the door she would bring more experience on the bench, and more varied experience on the bench, than anyone currently serving on the United States Supreme Court had when they were appointed."
Sen. Leahy, D-Vt., Chair of the Senate Judiciary Committee:
"Judge Sotomayor has a long and distinguished career on the federal bench. She has been nominated by both Democratic and Republican presidents, and she was twice confirmed by the Senate with strong, bipartisan support. Her record is exemplary. Judge Sotomayor's nomination is an historic one, and when confirmed she will become the first Hispanic Justice, and just the third woman to sit on the nation's highest court. Having a Supreme Court that better reflects the diversity of America helps ensure that we keep faith with the words engraved in Vermont marble over the entrance of the Supreme Court: 'Equal justice under law.'"
Sen. Jeff Sessions, R-Alabama, ranking member of the Senate Judiciary Committee said in a statement:
"The president's nomination of Sonia Sotomayor to the Supreme Court today is an important step in a constitutional process that includes the advice and consent of the Senate. I congratulate Ms. Sotomayor on her nomination.
"The Senate Judiciary Committee's role is to act on behalf of the American people to carefully scrutinize Ms. Sotomayor's qualifications, experience, and record. We will engage in a fair and thorough examination of Ms. Sotomayor's previous judicial opinions, speeches, and academic writings to determine if she has demonstrated the characteristics that great judges share: integrity, impartiality, legal expertise, and a deep and unwavering respect for the rule of law."
"Of primary importance, we must determine if Ms. Sotomayor understands that the proper role of a judge is to act as a neutral umpire of the law, calling balls and strikes fairly without regard to one's own personal preferences or political views."
Sen. Charles E. Schumer, D-NY:
"This is an historic choice, and much more. Judge Sotomayor meets three very important standards in filling this Supreme Court vacancy -- excellence, moderation and diversity. First, she is a top-of-the-class legal mind who achieved the very highest honors at the nation's foremost academic institutions. Second, she is a moderate who was selected for the District Court by the first President Bush and was confirmed with Republican votes. Unlike the last President Bush, who solely sought nominees from the extreme right for the High Court, President Obama has not reached to the far left end of the spectrum to fill this vacancy. "
Sen. Minority Leader Mitch McConnell, R-Ky.:
"Senate Republicans will treat Judge Sotomayor fairly. But we will thoroughly examine her record to ensure she understands that the role of a jurist in our democracy is to apply the law even-handedly, despite their own feelings or personal or political preferences.
"Our Democratic colleagues have often remarked that the Senate is not a 'rubber stamp.' Accordingly, we trust they will ensure there is adequate time to prepare for this nomination, and a full and fair opportunity to question the nominee and debate her qualifications."
Joe Solmonese, president of the Human Rights Campaign:
"We applaud President Obama for choosing Judge Sonia Sotomayor to become our nation's next U.S. Supreme Court Justice. The U.S. Supreme Court decides cases that intimately affect the lives of all Americans. We are confident that Judge Sotomayor has a demonstrated understanding and commitment to protecting the liberty and equality of all Americans."
Cesar Perales, president and general counsel of Puerto Rican Legal Defense and Education Fund. Sotomayor is a former LatinoJustice PRLDEF board member.
"Sonia is a member of our family and spent more than a decade providing leadership to our organization. We profited firsthand from her probing mind as well as her thoughtfulness beyond her extraordinary intellect. She is a most practical person who found solutions to complex issues… We are prepared to engage those who would unfairly tarnish her reputation. The nation needs to know that LatinoJustice PRLDEF will come to her defense."
Wendy E. Long, counsel to the Judicial Confirmation Network, a conservative organization that focuses on Supreme Court nominations:
"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. She thinks that judges should dictate policy, and that one's sex, race, and ethnicity ought to affect the decisions one renders from the bench.
"She reads racial preferences and quotas into the Constitution, even to the point of dishonoring those who preserve our public safety. On September 11, America saw firsthand the vital role of America's firefighters in protecting our citizens. They put their lives on the line for her and the other citizens of New York and the nation. But Judge Sotomayor would sacrifice their claims to fair treatment in employment promotions to racial preferences and quotas. The Supreme Court is now reviewing that decision."