Pres. Obama took the quick and easy path by nominating Hon. Sonia Sotomayor to replace David Souter on the Supreme Court.
First, she's a two-party appointee. Pres. Bush (I) appointed her to a Federal district court bench during his sole term in office, Pres. Clinton appointed her to the Second Circuit Court of Appeals (which handles appeals from cases filed in district courts in New York, Connecticut and Vermont).
Second, she is female. As only the third female nominee, she'll receive great deference from the Senate (only three Senators total have voted against a female Supreme Court appointee -- the three dissenters to Justice Ginsburg).
Third, she is Latina. This is the minority category du jour that "deserves" a place on the Supreme Court. Miguel Estrada would have been the first undoubted Latino to serve on the Supreme Court if the Democrats had not filibustered his Court of Appeals nomination under Pres. Bush (II). Whether Justice Benjamin Cardozo (served 1932-38) was Hispanic is an open question.
Fourth, her paper trail, while not overwhelming the average Rhodes Scholar for its intellectual content, is not overly controversial. For a Democrat's nominee to be "controversial" to the media, the nominee would have to take opposite positions on Iraq War or War on Terror issues (Elena Kagan) or have doubts about the legality of abortion. For such a nominee to be controversial in general, the nominee would have to espouse a judicial philosophy that questions whether the law should be applied as written. Her comments that a wise Latina woman with the experiences of growing up poor, female, and Latina should reach the right conclusion in a case more often than a white male who was never poor nor Latino, is nonsense and preposterous on its face. It's the same "empathy" quality that elevates the feelings of the litigants over the rule of law. But it's less easy to challenge her dedication to the rule of law than Obama's alleged favorite.
Obama had a Supreme Court candidate whose dedication to the rule of law is highly questionable. That candidate was Diane Wood, a judge on the Seventh Circuit Court of Appeals. She seemed to be the favorite of liberal interest groups and the professoriat because she supposedly has the intellectual candlepower to go toe-to-toe with Scalia and Roberts. That's highly unlikely. But Wood was also the most controversial candidate possible precisely because her dedication to the rule of law is more open to question than any of the other rumored candidates (Kagan, Michigan Gov. Jennifer Granholm, Sotomayor). After Sen. Jon Kyl said Republicans would fight any nominee who placed empathy over analysis (a shot at Wood), Sotomayor became the most logical pick.
Possibility of her nomination passing the Senate = 100%.
Possibility of her appointment passing without dissenting votes = 45%.
Possibility of her reasoning in decisions ever being equally persuasive as Scalia's = 0%.