Nationals leader Warren Truss is promising to spend an extra $33 million on sealing more of an outback highway joining Queensland, the Northern Territory and Western Australia.

The 2,800 kilometre Outback Way is a series of roads and tracks between Winton in Queensland and Laverton in Western Australia, and is sometimes referred to as "Australia's longest shortcut".

Much of it is dirt and Mr Truss today will pledge the $33 million over three years towards sealing more of its length.

The estimated cost of completing the Outback Way is estimated to be about half a billion dollars.

The Nationals say the road link will be good for remote communities along its path.

The Coalition is putting a lot of resources into winning the Territory seat of Lingiari at this election.

Lonigiari covers an area of more than 99 per cent of the Territory, and is currently held by Labor's Warren Snowdon.

The Outback Way consists of seven interconnecting roads and highways.

It passes through the deserts of central Australia and has long been touted as a development to link Australia's east and west coasts via the Red Centre.