Australian Prime Minister Kevin Rudd and conservative rival Tony Abbott went head-to-head Sunday in the first debate of the election campaign, an encounter which focused on the economy and divided viewers.

Rudd, whom some commentators said looked nervous initially and appeared to check his notes, called for a "new way of politics" and promised to introduce a bill to legalize same sex marriage within 100 days of re-election.

"A new way of politics which puts to bed wall-to-wall negativity and puts to bed the politics of division and gets industry and unions and government around one table focusing on our country's future," Rudd said.

Abbott, a veteran politician who served as a minister in John Howard's government, countere Rudd's argument by saying that a new way of government would require an end to Labor's six years in power and a change of leadership.

Rudd kicked off the hour-long televised debate in the national capital Canberra stressing his center-left Labor government's credentials in keeping the economy out of recession during the global financial crisis.

"This economy is strong. This election is about the future strength of our economy and how best to secure it," he said.

"The election is about a clear choice on the economy, on jobs, on how we support families under (cost of living) pressure, and how we support education and health," Rudd added.

The election comes as the decade-long resources boom is beginning to unwind, with the central bank this week scaling back its near-term forecasts for economic growth.

Abbott, who leads a conservative Liberal/National coalition, which is narrowly ahead in opinion polls, said a government he led would strengthen the economy, as he committed himself to abandoning Labor's industry tax on carbon pollution.

"We can't afford another three years like the last six," Abbott said. He also vowed that his government would stop asylum-seeker boats embarking on the dangerous journey to Australia.