Some 6.4 million Austrians aged 16 and up were eligible to vote, with pre-election polls forecasting that Kurz's People's Party would come first and likely return the 33-year-old to power. The Alpine country of 8.8 million has been run by a non-partisan interim administration since June, after the publication of a video showing long-time Freedom Party leader Heinz-Christian Strache appearing to offer favors to a purported Russian investor triggered the Kurz government's collapse.
If opinion polls are accurate, Kurz will have to choose whether his conservative People's Party will form a fresh coalition with a chastened Freedom Party or team up with the center-left Social Democrats. Both were running neck-and-neck ahead of the vote.
"To go back to the Freedom Party, in the current situation this would be very difficult," said Peter Hajek, a political analyst, but added that "the chemistry with the Social Democrats just doesn't work."
The Social Democrats, which have led many of post-World War II Austria's governing coalitions, have failed to capitalize on the government's collapse under leader Pamela Rendi-Wagner. Hajek said other options could see Kurz team up with the environmental Greens and the pro-business Neos, or with just the Greens. Kurz has made clear that he's prepared to consider every option to stay in power.
"Our most important election goal is to prevent a majority against us," Kurz said Sunday at a polling station in Vienna. The only realistic alternative to a Kurz-led government would be a three-way alliance between the Social Democrats, the environmental Greens and the pro-business Neos.
The Freedom Party's new leader, Norbert Hofer, has tried to rally supporters by stoking fears about immigration and Islam. In the final days of campaigning, he also took a swipe at climate activists who have staged mass demonstrations in cities worldwide, including Austria, demanding swifter action against climate change.
Kurz's People's Party won the 2017 election with 31.5% of the vote, with the Social Democrats taking 26.9% and the Freedom Party 26%. Exit polls will be released shortly after voting ends at 5 p.m. (1500 GMT).