The White House will announce shortly a shake-up of several of President George W. Bush's key advisers, a spokesman said. Spokesman Scott McClellan said the impending changes were discussed Monday by Bush's new chief of staff, Josh Bolten, at a White House meeting. "Josh talked about how this is a time to refresh and reenergize the team and for all of us to renew our commitment as we go forward," McClellan told reporters, without tipping his hand as to which posts might be reassigned. The planned revamping comes as speculation mounts over the future of US Defense Secretary Donald Rumsfeld, after recent calls by several prominent retired generals for his resignation. According to recent media reports, Treasury Secretary John Snow's days may also be numbered. But for now, McClellan confined his remarks to the openings that have already been announced. "Obviously the OMB (Office of Management and Budget) is vacant. We have been moving forward on that," he said, speaking about the post held until recently by Bolten. He replaced Bush's longtime chief of staff Andy Card.