MALCOLM Turnbull is openly defying Opposition Leader Tony Abbott over his new direction on gaming policy.

In a video tribute from anti-gambling advocate Tim Costello posted on Mr Turnbull's website, Mr Costello praises Mr Turnbull for his "leadership" in backing tough reforms on problem gambling.

Only a week after Mr Abbott indicated a Coalition policy would rely heavily on a voluntary pre-commitment scheme, Mr Costello said the measure would not work.

"Problem gamblers just will not do it. Voluntary pre-commitment is a contradiction in terms," Mr Costello said.

Mr Abbott's discussion paper had outlined plans to seek written advice about the feasibility of a national voluntary pre-commitment program.

It followed Mr Turnbull's refusal last month to back his leader's vow to roll back Labor's proposed mandatory pre-commitment technology if the Coalition won government.

Liberal sources said Mr Turnbull's ambition for leadership had not waned, and he was becoming "active" again.

Originally published as Defiant Turnbull taking a gamble