The Senate is expected to begin his confirmation hearings as chief justice either Thursday or next Monday. The opening of Roberts' previously scheduled confirmation hearings, for the position of associate justice, initially was to be Tuesday, but that was canceled until after Rehnquist's funeral on Wednesday.
CBS News' Gloria Borger said the move could solve two problems for the president. If confirmed, Roberts would give the court a new chief justice when it starts its next term. Also, the court would have a full slate of justices to hear cases. That's because retiring justice Sandra Day O'Connor has agreed to stay on until her replacement is found.
CBS News Correspondent Wyatt Andrews reports that Roberts appeared emotional when he discussed William Rehnquist, who he once clerked for and considered a role model.
"I am honored and humbled by the confidence the president has shown in me," Roberts said, standing alongside Bush in the Oval Office. "I am very much aware that if I am confirmed I would succeed a man I deeply respect and admire, a man who has been very kind to me for 25 years."
"He's a man of integrity and fairness and throughout his life he's inspired the respect and loyalty of others," Bush said. "John Roberts built a record of excellence and achievement and reputation for goodwill and decency toward others in his extraordinary career."
The selection of Roberts helps Bush avoid new political problems when he already is under fire for the government's sluggish response to Hurricane Katrina and his approval ratings in the polls are at the lowest point of his presidency.
CBSNews.com Legal Analyst Andrew Cohen said Bush's move would help the president on three fronts.
"It's a decision by the White House that makes sense practically, politically, and legally — a rare trifecta these days. With one deft change of direction, the president all but ensured we will have a new chief justice in place four weeks from now, when the new court term begins," Cohen said.
"At the same time, he placed Senate Democrats in a box from which they are unlikely to be able to escape. And, finally, he gave himself some room to nominate a successor to Justice O'Connor who is perhaps even more conservative than is Roberts," he added.
Despite the brief delay in beginning hearings, Senate Majority Leader Bill Frist, R-Tenn., said he still expects Roberts to be confirmed before the new court session begins on October 3.
"The president has made an excellent choice," Frist said. "Mr. Roberts is one of the most well qualified candidates to come before the Senate. He will be an excellent chief."
Democrats said Roberts will now be held to a higher standard, although they had found little in his record to suggest they would thwart his nomination as associate justice.
"Now that the president has said he will nominate Judge Roberts as chief justice, the stakes are higher and the Senate's advice and consent responsibility is even more important," Democratic leader Harry Reid said Monday in a statement. "The Senate must be vigilant."