OTTAWA -- The front-runner in the race to become Canadian prime minister, Paul Martin, came under attack from his rivals on Saturday for portraying himself as the candidate of change despite his nine years as a senior minister.

As finance minister in the Liberal government from 1993 until a year ago, Martin was the second most powerful man in government, and his successor in that post, John Manley, marveled that Martin should talk now about taking government in a different direction, Reuters reported.

"In his suggestion that somehow or other he represents change, he is trying to distance himself from policies which he was very personally and directly implicated in," said Manley, one of Martin's two rivals in the Liberal leadership race.

Manley spoke after a debate between the three candidates vying to replace Prime Minister Jean Chretien who has pledged to step down next February. Because the Liberals control Parliament, the Liberal leader will automatically become prime minister.

Manley also accused Martin of "leadership by waffling" on whether Canada should ratify the Kyoto Protocol on climate change, and the third candidate, Heritage Minister Sheila Copps accused him of leading legislators who opposed last year's ratification.

"His gang tried to derail it," Copps told reporters afterward, though she failed to land any punches on Martin during the actual debate.

Though the new Liberal leader will not be chosen until a convention in November, the debates are being held now because of a June 20 cutoff for party members who will choose delegates to that convention. The last debate is next Saturday in the province of Quebec.

Martin's apparently overwhelming grip on the Liberal Party -- which helped force Chretien to agree to step down -- was demonstrated on Saturday in the fact that almost all the supporters in the cavernous hall watching the debate were his.

Both Martin and Manley are from the fiscally conservative wing of the Liberal Party and are collectively responsible for a string of rare budget surpluses, but Manley has come out during his campaign for strong central government and on Saturday he advocated federal spending on high-speed rail.

Copps hails from the left wing of the party and is seen as having only an outside chance at winning.