President George W. Bush on Tuesday chose as his first Supreme Court nominee U.S. Circuit Judge John Roberts Jr., a conservative whose selection pleased Republicans and prompted Democrats to vow a thorough review in the Senate. If confirmed by the Senate, Roberts would replace retiring Justice Sandra Day O'Connor, who gained a reputation as a moderate swing voter in her 24 terms on the nation's highest court. Bush called the selection of a nominee to the high court "one of the most consequential decisions a president makes." Bush's announcement, televised nationally in prime time Tuesday from the White House, ended nearly three weeks of fervent speculation about who would take O'Connor's pivotal place on the court. A senior administration official told CNN that Bush interviewed Roberts Friday at the White House and made his final decision Tuesday morning. He called Roberts about 12:30 p.m. to offer him the appointment. With Roberts standing at his side, Bush said the nominee "has devoted his entire professional life to the cause of justice and is widely admired for his intellect, his sound judgment and personal decency." In a brief statement, Roberts said, "It is both an honor and very humbling to be nominated to serve on the Supreme Court."