National Party leader Mark Vaile insisted today that his switch to a domestic portfolio “was not a concession that his party was in serious trouble.” He admitted that “from time to time, we have mixed fortunes”, and said he wanted “to ensure we have our best opportunity at the next election to increase our numbers.”

Of course it’s ten years since the Nationals increased their numbers at an election, and no-one expects them to do it this time: Vaile’s task is to stop their numbers declining further. For some interesting thoughts on the problem he faces, it’s worth having a look at Glenn Milne’s piece in this morning’s Australian.

Milne’s theme is that the lack of a credible successor to Vaile is “a threat to the future viability of his party”, and he suggests that Lawrence Springborg, former Queensland opposition leader, could switch to federal parliament with a view ultimately to becoming leader. He also reports talk that Springborg could become a candidate for the current round of Senate preselection.

It may be, however, that Milne takes the National Party too seriously as a going concern. Unless it can improve on recent performances, the Queensland Senate preselection is largely academic. Barnaby Joyce only won a seat because the Coalition vote last time was strong enough to elect four senators; had there only been three, they would almost certainly have all been Liberals. The Queensland Nationals have declined from two-thirds of the Coalition Senate vote in 1983 to just one seventh in 2004.

The story is much the same in the House of Representatives. On my count, eleven Liberal seats have been won from the National (or Country) Party, but there are none the other way around: every seat the Nationals have ever won from the Liberals has since been lost again.

Milne talks up National prospects in Leichhardt and Richmond, and points out that Page – whose National MP may be retiring – “contain[s] safe National Party state seats”. In reality, the greater part of it is in the state seat of Clarence, where the Nationals have a margin of only 1.6%. But even the safe areas are safe only because the Liberals never run against them; put Liberal candidates onto the NSW north coast and the Nationals’ prospects start to look very different.

The lesson is that the National Party has more immediate threats to its future than Vaile’s succession. After all, he is only 50: if the party still exists when he hits retirement age, that will be achievement enough.