President Bush's chief liaison to Congress, Nicholas Calio, told White House colleagues on Tuesday that he is resigning to return to private-sector business.

Calio, who announced his departure in the regular morning meeting of senior White House staff, is the latest top presidential aide to leave voluntarily at the administration's midpoint, a traditional time for turnover.

As assistant to the president for legislative affairs, the same job he held under Bush's father, Calio is credited with shepherding the president's signature education overhaul and $1.35 trillion tax cut through Congress last year.

Calio said he told Bush several weeks ago that he and his family decided on a change. On Tuesday, he made it official and set a Jan. 10 departure date.

In his resignation letter to the president, Calio paid tribute to a White House staff who worked as a team "without jealousy or regard to who got credit.''

"We work hard, we like each other and we have fun,'' Calio wrote. ". ... It is difficult to leave all of this behind. My reasons for leaving come simply to the two 'Fs' — family and financial.''

Calio and his wife, Lydia, have one daughter in college and two more children soon to be facing college tuition.

He said he was now choosing among "good opportunities'' in the private sector.

To take the White House job in January 2001, Calio gave up his highly lucrative partnership in O'Brien Calio, the lobbying firm he co-founded in 1993. There, Calio represented such clients as Anheuser Busch, AT&T, Boeing Corp. and Merrill Lynch.

Mary Matalin, top public-relations strategist to Vice President Dick Cheney, made her resignation official last week. Joe Allbaugh said Monday he will step down in March as director of the Federal Emergency Management Agency.

Treasury Secretary Paul O'Neill and White House economic adviser Larry Lindsey were earlier forced out in a housecleaning designed to limit the political damage to Bush of a sputtering economy.