President George W. Bush nominated conservative appeals court judge John Roberts on Monday to replace the late William Rehnquist as Supreme Court chief justice, the top judicial position in the United States, Reuters reported. U.S. Senate leaders agreed to delay the start of confirmation hearings for Roberts until at least Thursday and no later than next Monday, out of respect for Rehnquist. The hearing had originally been set for Tuesday. "Judge Roberts has earned the nation's confidence, and I'm pleased to announce that I will nominate him to serve as the 17th chief justice of the Supreme Court," Bush said in the Oval Office with Roberts at his side. The choice was to a certain degree a sentimental one, given that Roberts was once a law clerk for Rehnquist, who died on Saturday of thyroid cancer. It was also a shrewd political move because, as a newcomer already nominated to serve as one of the high court's eight associate justices, Roberts' background and credentials have been scrutinized and no major obstacles found. Rehnquist's death at age 80 left a rare two openings on the high court and gave Bush the chance to move it to the right for decades to come. The Supreme Court interprets the U.S. Constitution and is the final arbitrator on such hot-button issues as civil rights, abortion rights and gay rights. --more 2313 Local Time 2013 GMT