WASHINGTON  President Bush, warning that terrorists “would like nothing more than to exploit this period of change,” said Thursday that he intended to talk to President-elect Barack Obama on Monday about issues that will face his administration, including the turmoil in the financial markets and the war in Iraq.

The White House is especially concerned that the nation will be vulnerable during the transition between the Bush and Obama administrations. In one sign of that, Mike McConnell, the director of national intelligence, flew to Chicago to present Mr. Obama with his first top-secret intelligence briefing on Thursday.

“For the next 75 days, all of us must ensure that the next president and his team can hit the ground running,” Mr. Bush said in an emotional speech to hundreds of employees of the executive branch on the South Lawn of the White House. He urged them to “conduct yourselves with the decency and professionalism that you have shown throughout my time in office.”

Mr. Bush has said he is determined to conduct an orderly transition. The White House wants to avoid a repeat of the kind of news reports that plagued President Bill Clinton when he left office amid questions about whether members of his staff, irked at having to turn their offices over to Republicans, removed the letter W from some computer keyboards.