PM confronted by SA local Rayleen Mullen

There's usually at least one pesky person at a prime minister's press conference.

But it's normally a journalist.

In Whyalla it was Rayleen Mullen, a Victor Harbor local who stumbled upon the man in the nation's top job while out walking her dog.

The ABC News van gave away that "something was happening" and she wasn't about to give up her chance to have her say.

So she bailed up Prime Minister Malcolm Turnbull as he wrapped up the press conference on the local Arrium steel works, issuing him a warning over international trade and Australian jobs.

"If there's another world war ... we wouldn't be able to exist," she passionately informed him on Wednesday.

"Where are our grandchildren, their children and their children going to work? You can't just have office jobs and health jobs."

Then a threat of sorts.

"I'm telling everybody, do an informal vote, that's telling all the parliamentarians we don't want you because we don't like what you all do," she said.

It was that comment that got under Mr Turnbull's skin, the prime minister issuing his own advice to Ms Mullen.

"Don't informal vote because that's a wasted vote," he said.

Ms Mullen told the prime minister her husband worked at the Arrium steel works and the couple used to have a steel business until they lost a government contract at the local police station.

After a few minutes local Liberal MP Rowan Ramsey came to his boss's rescue, politely telling Ms Mullen they had to go.

But the cameras were still rolling and Ms Mullen - who dials into local ABC radio frequently - wasn't going to waste her chance to grab the television spotlight.

In a press conference of her own, she told reporters she didn't know the prime minister would be there until she saw the television van.

"I thought, `Right I'm going to have my say'," she said.