(AP) WASHINGTON - Two Harvard-educated lawyers who made rapid ascents to power will briefly share the stage Tuesday at the presidential inauguration.

Barack Obama will be sworn in as president. The black-robed man on the other side of the Bible will be Chief Justice John Roberts.

The 53-year-old chief justice and his conservative leaning Supreme Court could have the last word on some of Obama’s most important policies.

And, with a lifetime appointment, Roberts figures to hold his job a lot longer than Obama occupies the White House.

In fact, if life expectancy and past Supreme Court tenures are any guide, Roberts could still be swearing in presidents in the 2030s.

The two longest-serving chief justices, John Marshall and Roger Taney, between them swore in every elected president from Thomas Jefferson to Abraham Lincoln. Marshall presided at nine inaugurations with five presidents; Taney administered the presidential oath seven times to seven men.

Roberts is the youngest chief justice since Marshall, who was 45 when he joined the court and remained there until his death at age 79. Another six presidential elections will be held before Roberts reaches that age.

Obama and Roberts spent about an hour together Wednesday at the Supreme Court. The chief justice invited Obama and Vice President-elect Joe Biden to visit with the justices, promising a warm welcome. They were all smiles in photographs of the private meeting released by Obama’s transition office.

The next president and the chief justice may be bound by their education, relative youth, political smarts and common roles as parents of young children, but they diverge sharply in their politics.

Indeed, as they face each other Tuesday, it will be the first time a president is sworn in by a chief justice whose confirmation he opposed. In 2005, Obama voted against Roberts after President George W. Bush nominated the then-appeals court judge as chief justice.

Roberts, it seems safe to say, probably also voted against Obama in the presidential election. The chief justice declined to be interviewed in connection with the inauguration.

It won’t be the first time that presidents and the chief justices who swore them into office have disagreed.

Marshall and Jefferson were political rivals who disagreed about the Supreme Court’s role as the interpreter of and highest authority on the Constitution. Marshall claimed that power for the court in the case of Marbury v. Madison in 1803.

Chief Justice Earl Warren and President Richard Nixon both were California Republicans, but Nixon campaigned for president in 1968 in part against what he saw as the liberal excesses of the Warren court.

Nixon’s inauguration in 1969 was the fourth and final one for Warren as chief justice. It was also, in the words of Warren biographer Jim Newton, "surely Warren’s least pleasant trip to that podium."