BUENOS AIRES, Argentina (AP) — Argentines are voting in party primaries that are seen as a litmus test for general elections in October with pundits closely monitoring support shown for President Mauricio Macri and a ticket involving ex-President Cristina Fernández.

Political parties hold their primaries simultaneously and voting is obligatory in Argentina, making them effectively an early poll ahead of Oct. 27 elections involving the entire electorate.

The front-runners are Macri and the presidential team of Alberto Fernández and his vice presidential running mate, Cristina Fernández. Alberto Fernández was the ex-president's chief of staff during her initial 2007-2011 term, and she surprised many by announcing that she would be his vice presidential candidate.

The pro-business Macri has the support of markets and Washington, but has lost popularity amid discontent over austerity measures and high inflation.