WASHINGTON – Under increasing pressure to revitalize his administration, President Bush reshuffled his economic team Tuesday 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.

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 for his skills, Portman’s nomination may help calm GOP anxieties about administration missteps. Portman is a close friend of Bush’s and has a reputation for being a skilled communicator regarding the economy, which will be a central theme for the November congressional elections.

The president tapped 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, Bush made clear that Defense Secretary Donald H. Rumsfeld’s job was safe, despite calls for 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.”

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.”

Tuesday’s changes were set in motion by the promotion of Joshua Bolten as Bush’s chief of staff from his previous position as budget director. Bush said 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.” Bolten will make suggestions “as to who should be here and who should not be here,” Bush said.