Treasurer Joe Hockey has called for opposition support for budget measures, following a commitment that the government will spend whatever it needs to defend Australia.

His comments came after a handful of backdowns on unpopular proposals to toughen welfare conditions for young people.

Prime Minister Tony Abbott has said costs associated with national security and the deployment of troops to Iraq are significant but manageable.

The government is committed to getting the budget back to surplus by 2024 and “broad balance” in four years time – with a deficit of $2.8 billion forecast.

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But Mr Abbott has ruled out increasing taxes to pay for the $630 million earmarked for Australia’s national security and the $500 million the involvement in Iraq is expected to cost per year.

Mr Hockey says Australia spends tens of billions of dollars on the Defence Force each year and the government is capable of delivering what it says it will.

“We will spend what we need to spend to defend our nation,” he told reporters in Washington.

He urged Labor to support the remaining budget measures to help pay for the mission in Iraq.