The marginal seat of Cowan is currently held by Liberal MP Luke Simpkins.
Earlier in the day, Labor claimed victory in the marginal seat of Frankston.
Younger was rewarded with the more marginal seat of Ayr, which he won in 1964.
In the inner-city marginal seat of Brisbane, the LNP increased their vote by 1.7%.
Hogan holds the marginal seat of Page on the New South Wales north coast.
In 1992 he was expected to win the marginal seat of Bury South but lost narrowly.
All three entered the House of Commons in 1964, Barnett for the marginal seat of Heywood and Royton.
At a media conference in the suburban Melbourne marginal seat of Deakin, Shorten suggested it was no "coincidence" the government had prevented CSIRO being questioned about the mine.
Burley is MP for the marginal seat of Cannock Chase and will be vulnerable to a Labour challenge if he retains the Conservative whip.
A byelection in Feeney's marginal seat of Batman in Melbourne could be challenging for Labor – the Greens are a genuine threat with preselected candidate, Alex Bhathal.
Turnbull had one campaign stop in the south-western Sydney marginal seat of Macarthur yesterday, while Shorten was in northern New South Wales.
