With betting markets forming a view that the Prime Minister is manoeuvring for an election a full year before it is due, his opposite number has picked an interesting time to voice support for fixed four-year terms.

Speaking at a meeting of business leaders last week, Bill Shorten reportedly backed his view with familiar arguments about the need for governments to be given more room to breathe, along with the undesirability of election timing being the plaything of opportunistic prime ministers — a matter that would be close to his heart as he prepares to face the trade union royal commission.

However, doubts about Shorten’s electoral prospects are far from the only reason why advocates of the idea shouldn’t be holding their breath.

The only item of constitutional reform that’s firmly on the agenda at present involves recognition for indigenous Australians, on which both parties are pursuing agreement with a view to proceeding with bipartisan support in 2017.

If a survey conducted by Newspoll a fortnight ago is any guide, this has excellent prospects for becoming only the ninth amendment to the constitution since federation, with 63% in favour, compared with only 19% opposed.

However, the fact that such a measure would be largely symbolic calls attention to the striking fact that projects to change the nation’s basic constitutional architecture have all but died out over the last quarter of a century.

The only referendum conducted in that time was the doomed republic proposal in 1999, which was likewise contrived to be as symbolic as could be managed.

While some learned authorities argued that a president chosen by a two-thirds majority of parliament was dangerously at odds with a finely calibrated status quo, supporters were very keen to emphasise that theirs was indeed a “minimalist” model that would leave the existing framework of government practically undisturbed.

The last time the public had the chance to do something more substantive was in 1988, and the results leave no room for mystery as to why no one has tried again since.

The four questions put forward on that occasion had been developed by a constitutional commission the Hawke government established to ensure its proposals would not have the appearance of a Labor power grab.

But by the time the referendum was held in September 1988, the government’s stocks were at a low ebb. Seeing an opportunity to capitalise, the John Howard-led Coalition ran a hyperbolic campaign against all four proposals that might have taught a young Tony Abbott a thing or two.

Denied the bipartisan support that has long been recognised as an essential precondition for any successful constitutional referendum, all four went down to heavy defeat.

Among them was a plan to introduce four-year terms — a reform that is now established at state and territory level everywhere except Queensland, evidently with strong public support.

Like any other failed constitutional referendum — which is to say, all but eight out of the 44 that have been held since federation — the rejection of four-year terms was thought by some to demonstrate the reflexive conservatism of voters who don’t make the effort to appraise themselves of the issues, or simply treat such occasions as an opportunity to take a swing at the government.

However, missing from the 1988 proposal was Shorten’s notion that terms should be not just be extended but fixed, which left it open to the entirely accurate charge that it simply granted more power and opportunity to the prime minister of the day.

With this qualification in mind, it might be thought that a proposal including fixed terms would be well placed to break the constitutional reform drought — particularly if supported by the conservative side of politics, which is currently taken with the notion that three-year terms are unduly burdensome for governments pursuing ambitious programs of reform.

There is, however, a rather large albatross around the neck of any notion that the federal Parliament should follow the example of the states, namely the Senate.

Senators currently serve staggered six-year terms according to a fixed cycle that is unrelated to the term of the House of Representatives, however obscure that fact may be to an electorate that has grown accustomed to voting for them both on the same day.

If Senate terms were left at six years under a regime of four-year terms for the house, separate Senate-only elections would become a regular occurrence. These national by-elections could hardly fail to go badly for the party in office, making the chamber an even bigger headache for the government of the day than it is already.

Since extending the Senate term to eight years would surely prove an impossible sell, the only thing for it would be to cut them to four, as was proposed in 1988.

However, the implications of such a change would not be limited to politicians’ job security. It would also mean an end to staggered terms — and with the Senate to be elected in its entirety on the same day as the house, the partisan make-up of the two chambers would become more alike.

For those who like to complain of “Senate obstruction”, that might well be thought a good thing. But this merely serves to emphasise that a compliant Senate is a weakened Senate — and history suggests that any proposal to that effect would have a big hurdle to clear in the shape of the smaller states, who have an effective veto through the requirement that referendums must secure majorities in four out of six states.

This point is neatly illustrated by the 1977 referendum on “simultaneous elections”, which sought to end the fixed six-year cycle so that senators would simply serve two parliamentary terms of indeterminate length, to begin and end at the same time as the term for the house.

The Coalition opportunistically opposed this when successive Labor governments put it forward in 1974 and 1984, but, in between, the Fraser government tried it on itself, with Labor remaining consistent in its support.

With both parties on side, the 1977 proposal was carried by thumping majorities in New South Wales, Victoria and South Australia, together with three further proposals put forward on the same day.

But in Queensland and Western Australia, the opposition of the conservative premiers, Joh Bjelke-Petersen and Charles Court, weighed decisively against it, while in Tasmania it went down to a resounding defeat.

This demonstrated that while bipartisan support is certainly necessary for a referendum to succeed, it is by no means sufficient — particularly in circumstances where the standing of the Senate is seen to be at stake.