LISBON, Portugal (AP) — Portuguese lawmakers are preparing for a landmark debate on whether to make Portugal one of only a handful of countries in the world allowing euthanasia and doctor-assisted suicide.

A debate in parliament Tuesday will end in a vote on four broadly similar bills tabled by left-leaning parties, including the governing Socialist Party.

The outcome is uncertain and is likely to be close, with many of the 230 lawmakers voting in accordance with their conscience instead of toeing a party line.

But even if one of the bills is approved, it could still be blocked by President Marcelo Rebelo de Sousa. The head of state has no executive powers but can veto legislation.

Rebelo de Sousa, reluctant to influence the parliamentary debate, hasn't said what he will do.