The Liberal National party looks certain to cruise to victory in a Queensland byelection, maintaining its numbers in the state’s tightly balanced parliament.

With almost 80% of votes counted in the Toowoomba South contest, the LNP candidate, David Janetzki, has claimed 46.2% of first-preference votes.

The banker is expected to fare well from pre-poll and postal votes, putting him on track to fend off independent former mayor Di Thorley in what is essentially a two-horse race. Thornley has secured 35.2% of first-preference votes.

The byelection comes after LNP MP John McVeigh vacated the seat before his successful election to federal parliament.

Labor didn’t run a candidate in the seat, which has been in either LNP hands or its parent party, the Nationals, since 1974.

Janetzki’s likely win will ensure the LNP opposition remains level with the state’s Labor government at 42 seats each in the state’s 89-seat hung parliament.

A Thorley victory would have offered Labor a slight edge, while increasing the powerful crossbench to six MPs.

The Queensland Electoral Commission is continuing its count.