Australia PM, defending slim majority, faces by-election test

Voting got under way in a by-election Saturday that could have serious ramifications for the Australian government, which faces losing its majority in parliament.

The poll in the suburban Sydney seat of Bennelong was triggered by a constitutional crisis that has seen eight parliamentarians resign over a once-obscure rule barring dual citizens from federal office.

They included Bennelong MP and former tennis star John Alexander, from Prime Minister Malcolm Turnbull's Liberal-National coalition, who stepped down after saying he was most likely a dual British citizen.

It was revealed later that he may not even be entitled to UK nationality and he is recontesting the seat against Labor's former New South Wales premier Kristina Keneally, a popular TV news personality.

Plenty is at stake, as the government battles falling voter support and internal division.

If Keneally wins, Turnbull's coalition would lose its one-seat majority. That means Labor could defeat the government in parliamentary votes if it has the backing of all five independents, or crossbenchers.

Polls show Alexander, who was once the world's number eight ranked tennis player, winning seven singles titles, as a slim favourite. He has held the seat for seven years.

"People will be casting a judgment on the government, which I lead, of course," Turnbull told reporters Saturday.

"Australia's security, prosperity, depends on John Alexander being back as part of our government, delivering more than 1,000 jobs a day."

The contest has been sharpened by recent political debate about increasing foreign interference, centred on China.

Bennelong has a large Chinese community and Labor has accused the government of whipping up hysteria.

The citizenship crisis came to a head on October 27 when Australia's High Court reaffirmed a provision in the country's 1901 constitution that forbids dual citizens from serving in federal parliament.

Of the eight parliamentarians forced to resign, two were from the lower House of Representatives and the rest were upper house senators.

The other lower house member, Deputy Prime Minister Barnaby Joyce, easily won his by-election earlier this month.

Voter support for Turnbull has eroded in recent months, with the Liberal leader having to bat away calls for him to step down, even from within the coalition.

Dissatisfaction has stemmed from frustration at dysfunction in Canberra, as borne out by the citizenship chaos, as well a perceived lack of leadership from the prime minister.

Bickering within the coalition has overshadowed some of his government's achievements and prompted questions over Turnbull's ability to bring the parties together.​