PORTLAND – John O’Leary, a former Portland mayor, will leave his post as U.S. ambassador to Chile on June 29.

O’Leary, who was appointed by President Clinton three years ago, is leaving to make room for a Republican appointee in the Bush administration. O’Leary, a former partner at Pierce Atwood law firm in Portland, plans a two-month vacation on Little Diamond Island in Casco Bay before returning to private practice, probably in Washington, D.C.

Mainers of both parties praised the job O’Leary did, starting with meeting with Maine salmon growers who complained that Chilean salmon farmers were engaged in unfair trade practices.

“He’s just very pragmatic and responsive. He tries to work things out,” said GOP Sen. Susan Collins, whose chief of staff, Steve Abbott, is a former law partner of O’Leary’s. “I’ve been very proud to have him as a Mainer representing our country so well.”

O’Leary, 54, said the best moment of the job came on Nov. 27, when President Clinton called Chilean President Ricardo Lagos to begin trade talks despite uncertainty about who would win the White House.

If a trade agreement were worked out, Chile would become only the fifth country to enjoy free trade status with the United States.

“Both presidents plainly seized the moment that was there,” O’Leary said. “That that could be done on the basis of a phone call reflected a level of trust and confidence personally between the two presidents and more broadly between their two governments. That was very gratifying.”

While many ambassadorship appointments are viewed as rewards to six-figure campaign contributors, O’Leary was never a large contributor to Democratic candidates, though he was a party activist.