President Bush nominated Gov. Paul Cellucci on Tuesday as ambassador to Canada, clearing the way for Cellucci's second-in-command, Jane Swift, to become the first woman governor of Massachusetts.
Cellucci said he would "proudly" accept the ambassadorship if confirmed by the Senate.
"Gov. Paul Cellucci is a friend and a fellow governor," Bush said in a written statement. "His appointment signifies the importance I place on the close relationship between the United States and Canada."
Cellucci, who has served as lieutenant governor or governor since 1991, would be the second governor in a row to leave the Massachusetts statehouse in midterm.
In addition to becoming the state's first woman governor, Swift, 35, is believed to be the first person who would serve as governor of a state while pregnant. She is expecting twins in June.
"I believe I'm up for the challenge," she said.
Cellucci, 52, is Bush's first ambassadorial appointment as president and was an early backer of Bush's presidential bid. He managed the Massachusetts presidential campaigns of former President George Bush.
On Tuesday, Bush cited Cellucci's experience in dealing with Canadian government leaders, negotiating issues such as energy, fishing and commerce.