Labour and National are clashing over a potential mega-tunnel underneath Wellington.
The government's looking at a tunnel connecting The Terrace and Kilbirnie, a distance of around 4km.
It has been proposed to bring down travel times and reduce congestion on state highways.
National's Mark Mitchell told Mike Hosking that they're going through a business case and analysis.
But Labour's Ginny Andersen, based in Lower Hutt, is sceptical about how it'll happen.
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