WASHINGTON – Newly installed White House Chief of Staff Joshua Bolten sent a clear signal on his first full day on the job Monday that a broader shake-up of President Bush’s politically troubled operation is imminent, asking aides who are thinking of leaving sometime this year to submit their resignations right away.

Bolten cast his ascension from federal budget director as the opportunity for “a fresh start” that will involve both new faces and new organization of the president’s team. Bolten has focused particularly on the administration’s legislative, communications and economics staffs.

Bolten, 51, has been authorized to restructure the way the White House works as he sees fit. Aides said he plans to begin changing internal processes within seven to 10 days. And Bolten wants to move quickly to bring in new people, starting with his own replacement by the end of the week.

Bolten used his first senior staff meeting Monday morning to indicate that personnel changes may be more significant than first anticipated. Bolten said that any who expected to move on by the end of the year should do so immediately, according to White House press secretary Scott McClellan.

The president’s closest advisers are expected to stay, including Deputy Chief of Staff Karl Rove, counselor Dan Bartlett, national security adviser Stephen Hadley and senior adviser Michael Gerson. But some other top officials had already been thinking about leaving later this year, according to co-workers, such as communications director Nicolle Wallace, whose husband moved to New York, and Deputy Chief of Staff Joseph Hagin.

And Bush on Friday issued a statement expressing “strong support” for Defense Secretary Donald Rumsfeld, who has come under fire from several retired generals.