Sotomayor will be the first Hispanic U.S. Supreme Court justice if confirmed
Obama plans to announce his nominee at 10:15 a.m. ET Tuesday, sources told CNN.
Obama said Saturday he wants intellectual firepower and a common touch in the next Supreme Court justice and said he doesn't "feel weighed down by having to choose ... based on demographics."
Obama's nominee will replace retiring Justice David Souter, who announced this month he would step down when the court's current session ends this summer.
There had been wide speculation that Obama would name a woman to the court, which has one female justice, Ruth Bader Ginsburg.
Obama also had been under pressure to nominate a Hispanic justice to the court, which has never had one.
Obama's nomination will have to be confirmed by the Senate Judiciary Committee and the full Senate.
The nominee is not expected to have difficulty being confirmed in the Democratic-controlled Senate in time for the new court session in October.The president has said he hopes to have hearings in July, with the confirmation completed before Congress leaves for the summer.