The stubbornly weak economy is darkening Maine’s revenue prospects for the next two years by more than $160 million, and the gloomy new figures will probably force Governor Paul LePage to issue a spending curtailment order in mid-December. The state’s Revenue Forecasting Committee prepared numbers Wednesday that will be presented to lawmakers Thursday. They show revenues lagging by $35 million this fiscal year and by $128 million for the two-year budget cycle starting next July. The state’s finance commissioner, Sawin Millett, said the biggest contributors to the red ink are under-performance of sales and corporate taxes. The governor’s curtailment order would cut back spending in select areas without affecting necessary services.