BUENOS AIRES (Reuters) - Argentina’s government has introduced a voting reform bill that could hurt the Peronist opposition in a mid-term election next year that will determine the legislative strength that President Mauricio Macri will have in the final two years of his term.

President of Argentina, Mauricio Macri gestures during a joint news conference with his Uruguayan counterpart, Tabare Vazquez at the Olivos Presidential residence in Buenos Aires, Argentina, October 24, 2016. REUTERS/Enrique Marcarian

The proposal would require the government to print unified election ballots listing all candidates, replacing the party-by-party ballot system that has benefited bigger groups such as the Peronists.

Since his 2015 election, Macri has lowered energy subsidies, cut grains export taxes and ditched trade and currency controls. The October 2017 mid-term election will decide whether he can get the rest of his free-market program through Congress.

Under current law, each party provides its own separate ballot sheet. To split a vote and cast one for another party requires another sheet, giving an advantage to larger parties, such as the Peronists, who can print more ballots and man more polling stations to make sure all their votes are counted.

Past elections have seen claims of voter fraud involving one party or another making the ballot sheets of their rivals disappear.

“The unified ballot will hit the bigger parties,” said Mariel Fornoni, an analyst with polling firm Management & Fit.

A government official familiar with Macri’s thinking was more explicit. “The reform will mean the end of the Peronist machine,” said the official, who asked not to be named.

The Senate is expected to vote on the bill in the coming weeks. Macri’s party is outnumbered in the Senate but he may be able to cobble together a coalition to pass the bill and send it to the lower house for final approval.

Peronism has been a huge force since Juan Domingo Peron burst onto the national scene as part of a coup in the 1940s.

Macri’s predecessor, Cristina Fernandez, is from a left-leaning branch of the Peronist umbrella. Macri is head of the much smaller PRO party, which has had success getting bills through Congress as part of his wider “Let’s Change” coalition.

“We do not believe in political machines,” Macri’s Chief of Staff Marcos Pena recently told Reuters. “We have a more contemporary view of politics.”

Macri was elected on promises of pulling Argentina out of a recession and attracting waves of foreign direct investment. Neither has happened so far. Industrial output shrank 7.3 percent in September versus a year earlier.