MANILA, Philippines (AP) — Philippine President Rodrigo Duterte's name is not on the ballot but Monday's midterm elections are seen as a crucial referendum on his rise to power with a brutal crackdown on illegal drugs, unorthodox style and contentious embrace of China.

Opposition aspirants consider the Senate the last bastion of checks and balances given the dominance of Duterte's loyalists in the lower house. An independent survey shows Duterte-backed candidates winning the race with only one from the opposition.

Duterte wants the elections to bolster his legislative agenda. That includes the return of the death penalty, lowering the age for criminal liability of child offenders and revising the constitution to allow a shift to a federal form of government, a proposal some critics fear may be a cover to remove term limits.