SYDNEY: Australia's Prime Minister Kevin Rudd warned upcoming elections would be "very tight" on Tuesday as the revamped opposition rose in polls following the defeat of controversial emissions trading laws.

Rudd confirmed the legislation would be introduced for a third time as the Coalition, now led by the colourful Tony Abbott, closed to within four points of the ruling Labor Party in the latest Newspoll.

"This will be a very, very tight election. It's always been my view," Rudd told reporters, urging his party "to be really on (its) game."

"Remember, the government's majority is what, eight seats? Two or three percentage points? Doesn't take much to move that," he said.

"If two or three people in a hundred change their vote then Mr. Abbott's the prime minister, that's the bottom line."

Rudd's emissions scheme, the centrepiece of efforts to slash carbon pollution by between five and 25 percent of 2000 levels by 2020, collapsed for a second time in December, just ahead of vexed climate talks in Copenhagen.

The opposition Liberal Party, dominant partner in the opposition Coalition, dumped its leader Malcolm Turnbull for supporting the scheme, replacing him with Abbott who strongly opposes the bill.

The Newspoll of 1,146 voters gave the Coalition 48 percent support, its best showing since 2007 elections, while dissatisfaction with Rudd rose four points to 38 percent, his highest level since becoming prime minister.

General elections could be held as soon as August with the lower house's term set to expire early next year.

Rudd defended his cap-and-trade programme as "the least costly and most effective way to deal with climate change," which had been endorsed by other governments around the world.

Abbott on Tuesday launched an alternative scheme proposing a billion-dollar (890 million US) fund to pay for cleaner power stations, tree-planting and trapping carbon pollution in agricultural soil.