(Adds details on public spending/earnings, context)
BUENOS AIRES, March 10 (Reuters) - Argentina's primary fiscal deficit widened sharply in 2015 to 5.4 percent of gross domestic product, official data showed on Thursday, with the increase in public spending outpacing revenue gains ahead of the last presidential election.
Taming the fiscal deficit is one of the top policy priorities of President Mauricio Macri, who won election in November and has slashed power subsidies and laid off tens of thousands of public workers in a drive to lower Argentina's bloated public sector wage bill.
The primary deficit, which does not include debt payments, grew to 291.66 billion pesos ($22.26 billion) in 2015, marking a 73 percent increase in peso terms.
The data showed public spending increased by 34.5 percent from the previous year, while government earnings increased 31.6 percent. Finance Minister Alfonso Prat-Gay estimates inflation was running at about 30 percent.
Former President Cristina Fernandez's leftist government spent heavily ahead of the election to spur domestic consumption in a bid to revive a stagnating economy.
In January, the primary deficit came to 548.0 million pesos, 91 percent narrower than the 5.77 billion peso deficit recorded in the same month a year earlier.
Argentina recorded a primary fiscal deficit of 3.8 percent in 2014, according to the finance ministry's latest data. ($1 = 13.10 pesos on Dec. 31) (Reporting by Hugh Bronstein and Richard Lough; Editing by Jeffrey Benkoe)