Former ambassador to the U.S. Frank McKenna speaks during an interview with the Associated Press in Washington in June 2005. (Gerald Herbert/Associated Press) Frank McKenna, a former New Brunswick premier, said Tuesday he will not run for the leadership of the federal Liberal party, putting an end to mounting speculation about his political future.

McKenna, who also served as a Canadian ambassador to Washington, was one of several high-profile Liberals aggressively courted to replace Stéphane Dion as party leader.

"Although I have been deeply moved by expressions of support for me from across the country, I have not been persuaded to change my long-standing resolve to exit public life for good. My only regret is that I cannot honour the expectations of friends and supporters who have shown enormous loyalty to me," said McKenna in a statement released Tuesday.

"The challenge of winning the leadership, restoring the health of the Liberal party and returning a Liberal majority government requires a longer time commitment than I am prepared to make," the statement read.

McKenna, 60, is viewed as a fiscal conservative and centrist who boasts impressive financial credentials. He will remain at his post as deputy chair of TD Bank Financial Group.

With McKenna now out of the Liberal race, other potential candidates like Bob Rae and Michael Ignatieff will feel their chances of taking the helm of the party have improved, said CBC News parliamentary editor Don Newman.

"In the short term, at least, it helps both Bob Rae and Michael Ignatieff," said Newman.

After winning the provincial Liberal leadership in 1985, McKenna led his party to a complete sweep of all 58 seats in the New Brunswick legislature in the 1987 provincial election. He resigned in 1997 despite his popularity in the province, fulfilling an earlier promise that he would only remain in politics for 10 years.

"This is the interesting thing about him. Very few people get out of politics on their own volition," said Newman.

On Oct. 20, Dion indicated he would step down as Liberal leader, almost a week after suffering an emphatic loss in the federal election that saw his party's seat total drop to 77 seats from 95. The Conservatives won with a minority government.

Earlier Tuesday, New Brunswick MP Dominic LeBlanc, son of former governor general Romeo LeBlanc, became the first Liberal to announce a leadership bid.

A leadership convention is likely to happen in Vancouver in May, where the party had planned a biennial policy conference.