Christie Whitman resigned May 21 as head of the Environmental Protection Agency, The Associated Press reported.

Whitman said in a letter to President Bush she was leaving to spend time with family.

"As rewarding as the past two-and-a-half years have been for me professionally, it is time to return to my home and husband in New Jersey, which I love just as you do your home state of Texas," she wrote Bush.

Whitman had a history of clashing with the White House, starting with the president's abrupt decision to withdraw from the international global warming treaty, the news service reported. She had been the administration's point person in rolling back environmental protections initiated by previous administrations.

Whitman, a former New Jersey governor, said her resignation would be effective June 27. She met with Bush at the White House Tuesday afternoon to inform him of her decision, the agency said.