WASHINGTON  —  Alienated by the "negative tone" of the Republican Party and married to a Democratic presidential candidate, Teresa Heinz is leaving the GOP.

The multimillionaire philanthropist and wife of Sen. John Kerry, D-Mass., said Friday she is "increasingly alarmed by the negative tone and shortsighted policies of the Republican Party."

On the environment, an issue she has long been active on, Heinz said the GOP was "heading in the wrong direction by rolling back the common sense environmental laws and regulations which have made our air and water cleaner and safer."

Heinz is the widow of Sen. John Heinz, a Pennsylvania Republican and heir to the Heinz food fortune who was killed with six others in 1991 when his chartered airplane collided with a helicopter.

She joined the Republican Party in 1971, the year she became a naturalized American citizen. The daughter of a Portuguese doctor, Heinz was raised in Mozambique.

The decision to switch parties was also prompted by Heinz' desire to vote for Kerry in the presidential primary, said spokeswoman Chris Black. Heinz has filled out the party-registration forms, which will be filed next week, Black said.

Heinz is registered to vote in Pennsylvania, where only registered Democrats can vote in the party's presidential primary.

Kerry, in a statement, said his wife "has shared with me her deep frustration about the direction of the Republican party ... I am appreciative of this expression of support and her enthusiasm for the challenges of the campaign ahead of us."