CANBERRA, Australia—A senior colleague of Australia’s Prime Minister Malcolm Turnbull said Friday his conservatives have won closely-fought national elections, although Mr. Turnbull stopped short of declaring victory ahead of an official tally.
Preliminary results from Saturday’s elections give Mr. Turnbull’s conservative Liberal-National coalition 73 seats in the 150-seat lower house—where governments are formed—just short of the 76 needed to govern outright, with six seats still in doubt. The main opposition Labor Party, led by former union boss Bill Shorten, has 66 seats.
“We’ve won again,” Christopher Pyne, a senior conservative, announced on Australian television. “That’s our sixth victory out of eight in the last 20 years. You’d say that we are an election-winning machine.”
A short time later, Mr. Turnbull told reporters he was “very confident” of retaining office, but was awaiting an official outcome.
For Mr. Turnbull, who called an early election partly to establish a new mandate for his government after ousting the unpopular Tony Abbott as party leader 10 months ago, a narrow victory—or a tied result where he needs the support of independent or small-party lawmakers to govern—would be a significant setback.
Mr. Turnbull had sought to make the vote about which party is best placed to steer an economy roiled by voter angst at the end of a long resources-boom. Australia is looking to diversify its economy and keep it growing even as other big commodity-producers such as Brazil and Canada stall.
As the mining boom has petered out in recent years, Australian leaders on both sides of politics have struggled to stay on the good side of voters and detractors in their own parties. Between 1975 and 2007, the average tenure of an Australian prime minister was nearly eight years. Lately, it is less than two years—the country has had five prime ministers since 2010.
The rise of antiestablishment lawmakers, especially in the upper house where laws are passed, risks gridlock on policies aimed at shoring up the country’s fragile economy. The outlook on Australia’s prized triple-A rating was downgraded to negative Thursday, with Standard & Poor’s saying the close result puts the country’s path back to budget surplus in danger.
Mr. Turnbull called elections in both houses simultaneously—a rare “double dissolution”—hoping to break legislative gridlock in the Senate by sweeping away opponents of his agenda.
The Senate outcome may not be clear until August, but early counting indicates the prime minister may face an even more restive band of lawmakers whose political views range from anti-immigration to free-trade skepticism.
With more seats up for grabs than in usual Senate elections, the quota to win a seat was reduced. Some, like far-right Queensland lawmaker Pauline Hanson, hold anti-immigration views. Others, like centrist Sen. Nick Xenophon, whose NXT party may claim several Senate seats, are skeptical of the benefits of free trade as Australia is trying to cut deals with India and Europe to reduce its reliance on China to drive growth.
Even though Mr. Turnbull’s conservatives held a strong lower-house majority in the last Parliament, a hodgepodge of fringe lawmakers advocating everything from souped-up cars to looser gun laws blocked legislation in the Senate, including budget measures.
Write to Rob Taylor at rob.taylor[a]wsj.com