WASHINGTON – Under pressure to revitalize his administration, President Bush reshuffled his economic team yesterday with a new budget chief who is highly regarded on Capitol Hill and promised more changes were coming. He also named a new trade representative.

Mr. Bush chose Rob Portman, a former six-term Republican congressman from Ohio who now serves as trade representative, to head the Office of Management and Budget, putting him at the heart of White House decision-making.

Hailed by Democrats and Republicans alike, Mr. Portman’s nomination may help calm GOP anxieties about administration missteps. Mr. Portman is a close friend of Mr. Bush’s and has a reputation as a skilled communicator about the economy, which will be a central theme for the November congressional elections.

The president tapped Mr. Portman’s deputy, Susan Schwab, to move up and replace her boss as the administration’s top trade negotiator with other nations.

Announcing the changes during a Rose Garden ceremony, Mr. Bush made clear that Defense Secretary Rumsfeld’s job was safe, despite calls for Mr. Rumsfeld’s resignation from a half dozen retired military commanders.

“I hear the voices and I read the front page and I know the speculation,” the president said testily. “But I’m the decider and I decide what’s best. And what’s best is for Don Rumsfeld to remain as the secretary of defense.”

Mr. Rumsfeld, at a Pentagon news conference later in the day, said he hasn’t considered resigning. “The president knows, as I know, there are no indispensable men. … He knows that I serve at his pleasure, and that’s that.”

Yesterday’s changes were set in motion by the promotion of Joshua Bolten as Mr. Bush’s chief of staff from his old job as budget director. Mr. Bush said Mr. Bolten, who moved into his new office last Friday, has a mandate to shake things up.

“With a new man will come some changes,” the president said. “And Josh has got all the rights to make those recommendations to me.” Mr. Bolten will make suggestions “as to who should be here and who should not be here,” Mr. Bush said.

With the Iraq war overshadowing his administration, his agenda stalled and his poll numbers at record lows, Mr. Bush faces calls from Republicans for fresh thinking and new energy. So far, Mr. Bush’s new choices have been confined to a small circle of Washington insiders. As trade representative, Mr. Portman already was a member of Mr. Bush’s Cabinet, and he will remain a member as budget director.

Lawmakers said Mr. Bush made a smart move by choosing Mr. Portman, who was highly regarded for his ability to forge compromises between Republicans and Democrats when he served as a member of the tax-writing House Ways and Means Committee and as vice chairman of the Budget Committee.

House Democratic Whip Steny Hoyer of Maryland said Mr. Portman and Ms. Schwab were “very capable, experienced individuals who have demonstrated their willingness to reach out and try to achieve bipartisan consensus on difficult issues and to make common-sense judgments based on the facts at hand.” Both nominations must be confirmed by the Senate.

Yet, Mr. Hoyer said Mr. Portman has a difficult job in taming deficits because “this administration has pursued the most fiscally irresponsible policies in American history.”

The House Budget Committee chairman, Jim Nussle, a Republican of Iowa, praised Mr. Portman’s “ability to work – with both sides of the aisle – as an extremely effective communicator and leader.”

Mr. Bush, at the announcement ceremony, noted Mr. Portman’s long experience on Capitol Hill and his successes – as trade negotiator over 11 months in opening new markets for American goods, and winning House passage of the Central American Free Trade Agreement.

“He knows the priorities of my administration,” Mr. Bush said. “He can get things done.”

“It’s a big job,” Mr. Portman said as he accepted the nomination. “The Office of Management and Budget touches every spending and policy decision in the federal government.”

The president acknowledged that Washington was buzzing with rumors about an administration shake-up. Treasury Secretary John Snow is said to be on the verge of leaving, and Mr. Bush has not risen to his defense the way he has with Mr. Rumsfeld. Republicans outside the White House say they expect changes in the White House lobbying and communications shops.

“I understand this is a matter of high speculation here in Washington,” the president said. “It’s the game of musical chairs, I guess you would say, that people love to follow.”

In another personnel change, Jim Towey, head of the White House office of faith-based and community initiatives, resigned to become president of St. Vincent College in Pennsylvania. White House press secretary Scott McClellan said Mr. Towey’s departure was not related to any White House shake-up.