While campaigning in the South Australian marginal seat of Boothby, the prime minister told residents at a retirement village he would not negotiate with other MPs should no party form a majority.

"I'm not going to do a deal on policy with the independents," he said.

"A vote for independents is a vote for Labor."

Mr Morrison also stressed he was seeking to form a majority government and warned against a minority parliament.

'I would say to people thinking about independents: one of our strengths has been majority government," he said.

The prime minister spent all of Wednesday campaigning in Boothby, held by the Liberals on a wafer-thin margin of 1.4 per cent.

While the coalition have held the Adelaide electorate since World War II, there's a strong chance it could fall into Labor hands.

After speaking with retirement village residents about the government freezing deeming rates, Mr Morrison spoke at a Liberal rally in front of other South Australian MPs and party candidates.

While he remained confident about the future, the prime minister said coming years would bring economic uncertainty, following the Reserve Bank raising interest rates.

"For many, many Australians with mortgages, that will mean a real impact," he told the crowd.

"What Australia will face in these three years beyond this election will be very tough."

He later did a street walk in the beachside suburb of Glenelg, following an announcement of a $14 million upgrade for the tourism precinct.

While he stopped to speak with voters, he was heckled by members of the public, with one saying the prime minister had "sold his soul to (Hillsong founder) Brian Houston".

The prime minister denied he was avoiding campaigning in key electorates where prominent independents are challenging moderate Liberals.

Prominent Liberals such as Josh Frydenberg in Kooyong and Dave Sharma in Wentworth are facing a surge in electorate support for independents.

"I will go where I believe it is best for my campaign for me to go, I'll flag where I go on the day," Mr Morrison said.

"I'm not going to be telecasting where I'm going each day, that's not something we do in campaigns."

It comes after a new Morgan poll released this week found support for independents has risen by 1.5 points to 9.5 per cent.

Mr Frydenberg said he did not take his seat for granted and admitted the battle for Kooyong was a tight contest.

"(Independents) don't have any detailed policies that they're putting forward, and they're not prepared to tell the community how they will vote in the event of a hung parliament," he told ABC TV on Wednesday.

"I'm up against the so-called independent who's a former member of the Labor Party."

Australian Associated Press