Murray MLA Murray Cowper said he had been fighting to extend the service to weekends since the five-day service between the two towns started three years ago.
But Murray Labor candidate Robyn Clarke claimed the Pinjarra 600 bus service was only extended to weekends after Murray shire councillors took the lead.
She said local people were fed up with the Liberals taking credit for other people’s work.
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Mr Cowper said the extra trips would also help seniors travelling for shopping and medical treatments, tourists and young people.
He said he would concentrate on adding new stops to the route, including North Pinjarra.
Ms Clarke said the Liberal Government had had eight years to deal with the lack of public transport in Pinjarra.
“I kicked off this campaign by meeting people in North Pinjarra and was shocked to hear about the lack of public transport in the area as well as Dwellingup, North Dandalup and Coolup,’’ she said.
She added that WA Labor had allocated $100,000 for the purchase of a mini bus for the service.