Tony Abbott is, as Crikey pointed out on Thursday, desperately trying to dodge the obvious comparisons between the demise of Victorian ex-premier Ted Baillieu and the ousting of Kevin Rudd. There are some differences, but they’re not ones the conservative side of politics may want to make too much of.

For one thing, if you’re going to roll a sitting premier or prime minister, the democratic time to do it is in the lead-up to an election, giving the voters a chance to cast their verdict. Rudd got to serve most of the term he was elected for, whereas Baillieu got little more than half. However, there’s another difference that speaks more to the differences between Labor and Liberal.

While Rudd’s unpopularity with the caucus was certainly the main reason behind him being dumped, there was also the fact the powerbrokers had an alternative they actually liked. Julia Gillard had performed superbly as deputy, and the caucus no doubt expected much better things than they got in the election. On the other hand, the MPs eager for Baillieu to go had a problem; they didn’t have anyone they saw as suitable, at least in the lower house.

There’s a familiarity in this. Campbell Newman was installed in Queensland based on an impressive vote-getting record at Brisbane City Council, but it is unlikely the risk of making someone outside the Parliament leader would have been taken if the party room had thought there was anyone on the inside who was up to the job. Colin Barnett had one foot out the door in WA before the party reluctantly turned to him because there was no one else.

The ALP’s problems are much belaboured. Good candidates can sit on the sidelines because they’re in the wrong faction or no faction at all. Moreover, the ceaseless conveyor belt from student politics through parliamentary staffer positions with diversions to the union movement or local government tends to beat the individuality out of candidates.

Nevertheless, there is no question that in these feeder leagues the Labor Party has a plethora of people capable of doing a decent job at least as backbencher or minor minister. It’s far less clear that the Liberals have this.

One can see the same dynamic even more clearly in the inevitable comparison between Craig Thomson and Geoff Shaw. Thomson’s preselection was an example of bone-headed factional stupidity. They had what looks like a perfectly good alternative in a cleanskin local candidate but chose not to take it, perhaps because important people owed favours to Thomson.

On the other hand, Shaw appears to have got the preselection by default. If there was a better candidate available, no one outside the party seems to have heard about it. The last Victorian election swept in plenty of dead wood, and not just in seats the Liberals never expected to win. It doesn’t seem this was the product of bad decision-making by the party so much as a lack of better alternatives. It doesn’t help, of course, if 52% of the population make up just 21% of your ranks.

This problem is far from restricted to state politics. At the 2010 federal election, eight preselected Coalition candidates were either dumped or withdrew thanks to various scandals and failings. In some cases the party might have been a little quick on the trigger, but surely this reflect a deep problem. Moreover, one surviving candidate had breached a domestic violence order and another was on the end of a withering judgment from a Supreme Court Judge.

In perhaps the most revealing case, the Liberals reopened preselection in one seat because they thought the selected candidate was not up to snuff, but in the end ran with her when no one better came forward. True, it was a safe Labor seat, but it was also Canberra —  it’s not hard to find people engaged with politics. Since then the candidate has been elected to the ACT Assembly. It’s possible the party misjudged her, but the shortage of alternatives is telling. It’s hardly surprising that if your party room is stuffed with people who aren’t much chop it will be hard to find good leaders among them.

The shortage of quality candidates is almost certainly a product of falling party membership. Although there are claims of a recent turnaround, it is generally accepted the membership of the Coalition parties, like that of Labor, is on the skids. It’s all very well to talk about bringing in star candidates who are not party members, but there is not necessarily a huge pool of suitable figures waiting in the wings. Moreover, long-term party membership provides an opportunity to learn the ropes, and for weaknesses to be exposed.

If the Liberal Party’s membership continues to decline there could be a lot more Geoff Shaws in its future ranks, and a lot more accidental leaders at the helm. These are problems that may prove even harder to address than the far more talked-about problems in the Labor Party.

*Stephen Luntz is the Victorian Greens’ electoral analyst and a partner at Above Quota Elections — the views here are his own