NICK MINCHIN has drawn the curtain on an 18-year career, citing his greatest achievement as defeating the republic referendum and lamenting his failures to speak out against the Iraq war and to force John Howard to resign in 2006.

After announcing his staged retirement before the last election, the Liberal party powerbroker and former finance minister bows out of Parliament at the end of this week.

On the way out ... Senator Nick Minchin. Credit:Andrew Meares

Giving his valedictory speech yesterday, Senator Minchin, who drove the push to replace Malcolm Turnbull with Tony Abbott as Liberal Party leader, rejected emphatically any human contribution to climate change.

He predicted Julia Gillard would follow Mr Turnbull and Kevin Rudd as victims of the war against carbon dioxide.