By ROD McGUIRKCANBERRA, Australia (AP) â¿¿ Prime Minister Kevin Rudd said Australia's election on Sept. 7 will be fought over who can be trusted to manage the Australian economy as it transitions from a decade-old mining boom that is fading. In starting the five-week election campaign, Rudd said the economy can no longer rely on Chinese demand for iron ore and coal that made the country one of the few wealthy nations to avoid a recession during the global economic downturn. "Who do the Australian people trust to best lead them through the new economic challenges that lie ahead?" Rudd asked at a news conference Sunday at Parliament House. Rudd conceded that his center-left Labor Party was the underdog, but opinion polls also show that more voters prefer the 55-year-old former diplomat to China as prime minister over opposition leader Tony Abbott, a former Roman Catholic seminarian and journalist who is also 55. The latest economic figures show a sharp decline in Australia's finances, with the Treasury Department last week raising its estimated deficit for the current fiscal year to 30.1 billion Australian dollars ($26.8 billion) due to the mining slowdown. The new forecast for the year ending June 30, 2014, was AU$12 billion worse than the department's last forecast in May. The government also announced a AU$33.3 billion shortfall in the revenue forecast over the next four years â¿¿ a deterioration of about AU$3 billion a week since the May forecast. Economic growth for the fiscal year, forecast at 2.75 percent in May, was downgraded on Friday to 2.5 percent. The conservative Liberal Party-led opposition coalition has accused the government of wasting money on stimulus spending. After Rudd announced the election date, Abbott promised to "get the budget back under control." Polls suggest the opposition faces an easier task picking up seats than Labor does. Labor holds 71 seats in the 150-seat House of Representatives where parties form governments. The opposition holds 72 seats, with the rest held by independents or sole legislators from minor parties.