(Bloomberg) -- Chile’s leftist contender Gabriel Boric is leading the first presidential polls since last week’s vote that set the stage for the country’s most divisive runoff since its return to democracy three decades ago.

Boric got 39% of voter intention, same percentage as last week, according to a Cadem survey published late on Sunday. The conservative candidate Jose Antonio Kast garnered 33%, down from 39% previously, while 28% of respondents said they were undecided.

The poll numbers came a week after Kast got 28% of the vote in the first round, followed by Boric with 26%. Chileans will return to the polls on Dec. 19 for the second round of votes to decide on either of the two candidates.

The runoff is crucial for the future of the nation’s free-market economic model which has propelled growth yet left many behind. Boric backs higher taxes, better public services and more equality, while Kast wants lower levies, a stronger role for the private sector and law and order.

The runoff will take place amid a backdrop of social unrest, as well as the drafting of a new constitution. Regionally, it comes ahead of 2022 elections in Colombia and Brazil that together may shift Latin America’s balance of power.

Last week, Boric secured backing from former presidential candidate Yasna Provoste, as well as Izkia Siches, who stepped down as head of a national doctors’ association to join his campaign. He also included former central bank President Roberto Zahler and professor Andrea Repetto into his economic team.

On Sunday, the Christian Democratic Party said it will support Boric in the runoff, saying Kast is a “threat to the constituent process and a return to authoritarianism that goes against democratic advances.” The party said in a statement that it doesn’t want to be part of a potential Boric government. 

Meanwhile, Kast gained the support of several political parties from the current center-right governing coalition. He also expanded his economic team by incorporating members such as former central bank board member Sebastian Claro and Jose Luis Diaz, founder of QFR Capital Management.

Economist Franco Parisi, who finished third with 13% of last week’s votes, still hasn’t announced his support for either candidate at the runoff.

The Cadem poll surveyed 1,000 people from Nov. 24-26. It has a margin of error of plus or minus 3.1 percentage points.

Another poll published earlier Sunday by local media showed wider differences with Boric leading with 40.4% support against 24.5% for Kast. The Pulso Ciudadano survey showed 15.5% don’t know who to vote for. The poll of 1,518 people had a margin of error of 2.5% and was carried out Nov. 23-26.

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