Federal Opposition Leader Tony Abbott says it takes stamina, grit and willpower to complete an ironman.

The 52-year-old has completed the Ironman Australia in Port Macquarie, on the New South Wales mid-north coast, taking just under 14 hours to swim 3.8 kilometres, cycle 180 kilometres and then run a 42 kilometre marathon.

Before the race, experts - along with Mr Abbott himself - claimed he had not put in enough training for a full ironman.

But he said he would "be a very happy man" if he could finish the race in 14 hours, and he managed that, with about two minutes to spare.

After a brief rest he even had enough energy to joke and speak with the waiting media.

Mr Abbott arrived on the course about 6am (AEDT) and said he was feeling ready for the challenge.

"I'm feeling pretty toey, this is going to be a huge challenge, but there's about 1,500 other people in it and it's just as big a challenge for them as it is for me," he said.

"I hope we all make it through OK."

He said the swim leg would be his toughest leg as he "swims like a brick".

"I think it will all be hard, you get out of the water, and then you've got a big challenge, and you get off the bike and then you've got another big challenge," he said.

"The thing is there'll be 1,500 people on the track - they are all heroes and legends in a sense and I am looking forward to their company."

As Mr Abbott predicted, it took him around an hour and a half to finish the swim, before looking stronger on the bike leg, which took him six hours and 43 minutes, finally completing the run in about five and a half hours.

It was a hot afternoon, with a brisk sea breeze and in the transition between the bike and the run legs, Mr Abbott said his body was starting to hurt and he expected to be "more like a tortoise than a hare" in the final leg.

Mr Abott used chocolate chip muesli bars, hot cross buns and smoked salmon and avocado sandwiches, as well as water and sports drinks to sustain himself during the gruelling race.

He looked relieved and happy as he crossed the finish line about 9pm, and after a brief rest the Opposition Leader spoke to the waiting throng of reporters and cameramen.

"John Howard was described as a man of steel by George Bush, why shouldn't I be an ironman in my own way," he said.

"Margaret Thatcher was the Iron Lady of British politics, why shouldn't Australian politics have an ironman."

Mr Abbott was easily recognisable on the course, especially during the bike leg when he wore black and bright pink riding gear.

He was a clear crowd favourite, receiving loud cheers and encouragement from spectators who lined the scenic and challenging course.

Mr Abbott says the level of support he received was "exhilarating".

"There are few things more exhilarating than the kind of crowd support you get at an event like this - if an election was held tomorrow in Port Macquarie, I think I'd win," he said.

He says running the country or running an ironman are both tough in their own way.

"In the end what you need is stamina and grit and willpower frankly - now I am not suggesting for a second that Kevin Rudd doesn't have all three of them - but I guess in my own way I have had to dig deep into wells of stamina and grit and willpower."