Lester said Twyford's idea "sounds outstanding". Darby said the first focus should be on students and children.
The idea comes a week after Auckland Transport raised many public transport fares to try to stay within a 47 per cent to 50 per cent cost recovery range. AT spends more than $400 million a year running the city's buses, trains and ferries.
It also follows a warning this month that Auckland's gridlock nightmare is set to escalate due to the city's unfettered growth. Severe congestion is expected to increase by 30 per cent at peak hours, and 50 per cent between the morning and evening peaks.
Last week, Auckland Council voted to proceed with more work on introducing tolls to charge motorists at different times of the day to change the time, route or way in which they travel.
Mayor Phil Goff also has plans for a regional petrol tax of 11.5 cents to fund transport improvements. The Labour Government has agreed to a law change to introduce the tax, which Goff wants in place this year.
"One of the best ways to reduce congestion is encouraging people to leave the car at home and take public transport," said Twyford.
"Better public services and cheaper fares may help us achieve that.
"This is an idea worthy of public debate."
Neither Goff or Auckland Transport could be reached for comment on the plan for cheaper fares.
Auckland's Public Transport Users Association welcomed the idea of increased subsidies to reduce public transport fares.
Spokesman Jon Reeves said Auckland has one of the lowest subsidies in the Asia-Pacific area and some of the highest fares.
He said the plan would give a boost for public transport and get cars off the road.
National's policy of a 50 per cent farebox for public transport was unrealistic and not widely used around the world, Reeves said.