As Austrians go to the polls on Sunday, it looks like Sebastian Kurz's conservatives are most likely to win, meaning Kurz may become Chancellor again.

Sunday's vote is being held in the wake of a video sting scandal in May that felled far-right leader and Vice-Chancellor Heinz-Christian Strache, blowing up his coalition with Kurz's party.

Yet Kurz has emerged largely unscathed and polls suggest his conservatives have even siphoned off voters from the far-right.

Kurz will, however, need a partner to gain a majority in parliament again. He might decide to go into a three-party coalition with the Greens and the liberals, pro-business Neos, or to revive his coalition with the far-right Freedom Party (FPO).

"Every vote for the FPO prevents black-green," FPO leader Norbert Hofer told his party's closing rally in a traditionally working-class district of Vienna, referring to a tie-up between Kurz's People's Party (OVP) and the Greens.

In the wake of the scandal, FPO has slid to around 20% from 26% in the last election in 2017. The OVP's has risen to around 34% from 31.5%.

The FPO has sought to confine the scandal's fallout largely to Strache, who offered in the sting video to fix government contracts at a dinner party on the holiday island of Ibiza with a woman posing as a Russian oligarch's niece. But a new potential scandal emerged this week.

Prosecutors said on Thursday that they are investigating Strache, as well as one of his former bodyguards and the former head of his office on suspicion of fraud.

The prosecutors' announcement followed media reports that the FPO funded a lavish lifestyle for Strache and his wife, who is an FPO candidate in this election.

Meanwhile, the FPO has doubled down on its anti-immigrant rhetoric, apparently hoping to shift the focus onto one of its core issues even though that has moved down the list of voters' concerns as Europe's migration crisis has eased.

"Islam is a system ... of subjugation and intolerance," Hofer told the rally. Austria has around 700,000 Muslims, roughly 8 percent of its population of just under 9 million.

FPO hardliner and former Interior Minister Herbert Kickl said other parties had "rolled out the carpet for Islam", adding: "When I am interior minister we will start pulling the carpet in, dear friends, bit by bit, centimetre by centimetre, and we will turn the carpet into a flying carpet."