The American politician John Nance Garner is better remembered for something he said rather than anything he did as Franklin Roosevelt’s vice-president.

That office, he famously observed, was “not worth a bucket of warm piss”. Initially toned down in newspaper reports to “spit”, Garner’s meaning remained unaltered: being deputy to the leader of the Western world wasn’t much fun.

Indeed, the same is true of most deputies in the political realm. Most are there to deputise – not lead – and the actual leader obviously has no interest in being eclipsed by a pretender to their hard-won throne.

Those presently bidding for the deputy leadership of the Scottish National Party would do well to remember this unfortunate reality, although the zeal with which some candidates are approaching the contest suggests they think the proverbial bucket is full of gold.

Although only one candidate (MSP James Dornan) has so far confirmed, according to recent reports about half a dozen others, mainly MPs, are giving “serious consideration” to running. The last two deputy leaders have been Westminster-based, runs one argument, and therefore so should the next.

Beyond balancing the leadership between Edinburgh and London, however, it’s difficult to see what the point is. When Stewart Hosie resigned in unfortunate circumstances a year-and-a-half ago, there was much chatter about the contest to succeed him giving the party an opportunity to review its strategy. Yet no such debate took place. Instead, a party loyalist and safe pair of hands – Angus Robertson – took over and everything went quiet.

The same chatter now surrounds the current vacancy, but I can’t find anyone (apart from the candidates) who are taking it at all seriously. “No one cares,” one former strategist told me. “The position doesn’t really matter.” That much is true, although prospective candidates’ interventions thus far are quite revealing about what passes for debate within Scotland’s governing party.

Perthshire MP Pete Wishart was first to offer his thoughts, calling for the “widest possible conversation” in a newspaper article. He, like others, focused on Brexit and the question of a second independence referendum, two inter-linked issues that will determine SNP fortunes over the next few years.

But while correct in identifying these as important matters, Wishart offered no real solutions. He chuntered on about crafting a “brand new” independence offering, as if alternative prospectuses can be purchased at a supermarket. Furthermore, he called on the party to “unite” the Yes movement and “span” differing views about the European Union, adding a pop at Nicola Sturgeon for “chastising” SNP Leave voters instead of wooing them.

Yet Wishart’s solution is almost exactly what the First Minister has already set out, “a graduated approach” in which an independent Scotland would rejoin the European Union via the European Economic Area and European Free Trade Association. This, he believes, would “bring back” Yes-Leavers who deserted the party last year, seemingly oblivious to the fact Sturgeon started outlining such an approach in late 2016 and it didn’t make the slightest difference.

At least, however, Wishart acknowledges there are problems, in the mind of MSP James Dornan everything is just dandy. He said yesterday he was “not convinced” that plans for a second referendum had anything to do with the SNP losing 21 MPs last June, rather nasty Unionists had “a clearly co-ordinated arrangement” to unseat high-profile Nationalists like Alex Salmond and Angus Robertson. This is otherwise known as a general election.

Not only does the Glasgow Cathcart MSP think a referendum is possible next year or the year after (virtually no one else believes this), but he doesn’t believe the SNP’s Leave supporters – perhaps around a third – pose any problem. Not a bit of it, once they see what a mess Brexit is, he claims, “they will be reconsidering their views on Brexit”. That’s a bit like saying some supporters of independence would become ardent Unionists if it all got a bit too difficult.

Such is the state of the modern SNP, a party in government and comfortably ahead in the polls but clearly moribund when it comes to internal democracy and realistic analysis. The same is true of Theresa May’s Conservative Party, and indeed a dearth of potential leadership talent is by no means a problem confined to Scotland’s governing party.

SNP MP Hannah Bardell, yet another figure contemplating a bid for the deputy leadership, spoke the other day of being in the “fortunate position” that there’s “no shortage of talent” among her colleagues in the SNP, yet judging by declarations thus far that’s a charitable view. Meanwhile at Downing Street, a hopeless Prime Minister is kept in situ partly because the alternatives – both internal and external – are so unpalatable.

Since the 1960s, SNP deputies have often gone on to become leader (a bit like vice-presidents in the United States), indeed the last four party chiefs all previously served as deputy, although that’s a pattern unlikely to be repeated next time round. And when the party was much smaller and less successful, a bright and able deputy could realistically hope to exert some influence over profile and strategy, but not now.

The other factor in all of this is the First Minister herself. Not only does Sturgeon maintain a tight leadership circle, but she has rather a lot on her plate at the moment; the idea that she’d welcome a new deputy with vastly different ideas about policy (not that there’s many of those) and strategy is rather far-fetched.

So, when the SNP’s next deputy leader is unveiled, most likely at its weirdly-timed June conference, I suspect it won’t change a thing. Nicola Sturgeon will still be in control and John Nance Garner’s bucket will remain full of warm liquid.