US President Barack Obama has nominated Solicitor-General Elena Kagan as the 112th justice to the Supreme¹ Court.

美国总统奥巴马提名副检察长艾琳娜·卡根为第112任最高法院大法官。

Ms Kagan, a 50-year-old former Harvard Law School dean, was at Mr Obama's side at the White House when he announced, as expected, that she was his pick.

She would be the youngest member and third woman on the current court, as well as the first justice in almost four decades not to have been a judge.

Republicans warned she would not receive automatic approval.

The Senate must confirm whether the nominee² - who has spent much of her professional life in academia - can replace retiring Justice John Paul Stevens, who is considered one of the court's leading liberals（自由主义者） .

Gay rights advocate

Democrats⁴ welcomed the nomination⁵, but Senate Republican leader Mitch McConnell said Ms Kagan's "brief litigation experience" would be reviewed.

If confirmed, she will become the fourth woman justice on the Supreme Court, following Sonia Sotomayor - also chosen by Mr Obama - Ruth Bader Ginsburg and Sandra Day O'Connor, now retired⁶.

Introducing Ms Kagan in the White House East Room as "my friend", Mr Obama said she would bring excellence⁷, independence, integrity（正直，廉正） and passion to the post.

The US president said she "is widely regarded as one of the nation's foremost legal minds".

Ms Kagan said she was "honoured and humbled⁸（谦卑的） by this nomination".

"I look forward to working with the Senate and thank you, Mr President, for this honour of a lifetime," she said.

Senate Judiciary Committee Chairman Patrick Leahy, a Democrat³, said Ms Kagan should be confirmed in the post by early September, after a hearing expected to last a week.

Once Justice Stevens retires, the Supreme Court will have no protestant judges.

Ms Kagan would be the third Jewish justice on the current court, along with six Catholics（天主教徒） .

The BBC's Richard Lister in Washington says Ms Kagan is regarded as a liberal on most issues.

But she has worked with conservatives and even attracted a liberal backlash（反斜线，后座） against her support for continuing Bush administration policies on state secrets and the use of military commissions to try terrorism suspects, our correspondent adds.

Her staunch advocacy（拥护，主张） of gay rights may concern Republicans.

She went through a fairly smooth confirmation⁹ process in the Senate for her current job this year, when seven Republicans voted for her.

With 59 votes, Senate Democrats would have enough to confirm her, but they would be one short of being able to halt blocking or stalling tactics（战术，策略） by any Republican senators.

Early in her career Ms Kagan was a clerk for a US Court of Appeals judge and later for former Justice Thurgood Marshall.

And like Mr Obama, she worked on the prestigious¹⁰ Harvard Law Review as a student.

Our correspondent says that selection of a Supreme Court justice gives a president the opportunity to influence US public life for decades, as the justices are not bound by term limits.