The Pheu Thai Party was ahead with 6.45% of eligible votes counted, followed by another opposition party, Move Forward, according to the election commission’s preliminary count.

The poll body was expected to announce its preliminary election results by 10pm local time.

The election pits a progressive opposition against parties backed by a nexus of old money, conservatives and generals at the heart of two decades of upheaval in Southeast Asia’s second-biggest economy.

An opposition win would bring no guarantees that either party would govern, however, even as an alliance, because of parliamentary rules written by the military after its 2014 coup that are skewed in its favour.

Electing a prime minister and forming a government requires the backing of a majority of the lower and upper houses combined.

The Senate was appointed by the former junta and is expected to vote in favour of parties or blocs allied with the military.

The election follows nine years of government led or backed by a military that staged two coups in the space of eight years against governments controlled by the billionaire Shinawatra family, Pheu Thai’s driving force.