Bush economic adviser stepping down

Al Hubbard, chairman of President Bush's National Economic Council, plans to step down on Wednesday, one in a growing line of top presidential advisers exiting the White House as the Bush administration heads into its last year.

Hubbard, assistant to the president for economic policy, will announce that he's leaving the White House after three years, according to a senior administration official, who spoke on condition of anonymity because the announcement had not yet been formally made. Hubbard is to submit a formal letter to the president later in the day.

His departure continues an exodus of key Bush aides and confidants. Earlier this month, Fran Townsend, Bush's terrorism adviser, announced she was stepping down after 4 1/2 years. Top aide Karl Rove, along with press secretary Tony Snow, Attorney General Alberto Gonzales, Defense Secretary Donald Rumsfeld and senior presidential adviser Dan Bartlett, have already left.

Among other issues, Hubbard has been deeply involved in the debate over State Children's Health Insurance Program and Bush's proposal for a major shift in tax policy to, for the first time, treat health insurance costs as taxable income.

He has not yet announced his future plans.