What do the years 1954, 1969, 1972 and 2001 have in common? They were rare occasions in which the major political parties contested a federal election on national security issues.

So-called khaki elections are unusual in Australian politics, bipartisanship having an almost sacred place on defence, foreign affairs and national security.

Matthew Guy tried it in Victoria a month ago and we saw how that worked out.

The Morrison government, as a new Sydney Morning Herald and The Age poll shows, enjoys a significant advantage with voters on border security, and on present indications it plans to play that advantage hard. If there is to be a national security dimension to the expected May election, that will be it.

Border security has had a heavily political slant since 2001, when the stand-off over asylum-seekers on Norwegian freighter the Tampa followed the September 11 attacks on the United States.