SANTIAGO — Chilean voters delivered conservative candidate José Antonio Kast the largest share of the vote in Sunday's presidential first-round election, forcing a December runoff, electoral authorities confirmed on Monday.

The vote unfolded with security, migration and crime dominating the campaign—issues that have reshaped Chilean politics since the social unrest of 2019. President Gabriel Boric is constitutionally barred from seeking a second consecutive term, leaving the left scrambling to retain power.

Kast, of the Republican Party, campaigned on hardline promises to seal Chile's northern border, expand police powers and expel undocumented migrants. His leading rival from the governing bloc emphasised pensions, wages and social spending, according to campaign statements reported by Chilean broadcaster TVN.

No candidate reached the outright majority needed to avoid a second round, with turnout bolstered by mandatory voting rules reinstated in recent cycles. The Servicio Electoral scheduled the decisive runoff for December.

The result signalled a continued rightward shift in a region where incumbents have struggled against voter anger over insecurity and economic stagnation. International observers said the process was conducted peacefully.