WA Labor leader Mark McGowan resists push for Treasury costings

WA Labor leader Mark McGowan has refused to agree to submit billions of dollars in campaign promises to Treasury during the leaders debate, saying the party already had a rigorous costings process.

Instead voters should throw out the Liberal National government that created the state's budget woes, he said.

Labor has attacked the Liberals over its financial management throughout the campaign, accusing it of blowing the mining boom proceeds, but is itself under pressure over how it will pay for its own expensive election promises such as its $2.54 billion Metronet public rail plan without increasing debt.

"We have a costings process for our policies. It is rigorous and we've got an ex-assistant auditor general and ex-assistant public sector commissioner engaging in that process for us," he said during the only debate ahead of the March 11 election.

Premier Colin Barnett accused Mr McGowan of "trashing" Western Australia and its reputation, saying he was proud of the state, that it had transformed during the eight-and-a-half years of his government and while the economy had struggled lately it was rebounding and people should have faith and trust him.

Mr McGowan said unlike Mr Barnett, who would step down during the term if he wins, he was in it for the long haul and would "put WA jobs first" by creating 50,000 jobs.