In presidential systems, it is clear who is a candidate for the position of heading government–anyone who enters the election as a formal candidate for president. What about in a parliamentary system? This seems like a trick question. I assume it is straightforward: A person who is the leader of a party can be assumed to be a candidate for prime minister.
We might qualify that definition of candidacy for prime minister by saying it only applies to the leaders of parties expected to be among the largest in the election. Perhaps leaders of clearly minor or sectarian parties can be dismissed as candidates for the post as they are deemed as highly unlikely to claim the post. However, in presidential systems, we would not define someone on the ballot as “not a candidate” just because he or she was considered unlikely to win the job. Is the standard different in parliamentary systems?
As a starting point, I do not really think it should be. “Candidates” who finish second, third, or even lower in votes in parliamentary elections occasionally do end up as prime minister, whereas only in very rare cases can anyone lower than second in votes become president (and being second in a final or sole round of voting can be sufficient currently only in the USA.*)
Our default, then, should be that, absent a good reason to believe some party is uninterested in heading the government, or no parties would ever let it do so, or that someone other than whoever is the formal party leader is likely to be prime minister should the party be able to fill the post, any party leader is a candidate for prime minister. However, this default may be incorrect, at least in the political discourse of any given parliamentary system.
Take the case of Israel 2021(a?). Twice during the campaign, statements about candidacy for prime minister have entered the media and inter-party conversation. In early March, Yamina leader Naftali Bennett made a statement that he was indeed a candidate for prime minister. At the time, my reaction was basically, no kidding. While his party would likely be too small for its leader to be PM, it does sometimes happen that some party within a coalition other than the largest provides the PM, and Bennett is his party’s leader and top-ranked candidate. Therefore, he is a candidate. Yet he felt there was political advantage in asserting so. In other words, what I called the “default” evidently is not.
Then more recently, Benjamin Netanyahu (the incumbent PM, leader of Likud, and most definitely a candidate for the top post in this election) said he would not debate opposition leader Yair Lapid unless the latter declares he is a candidate for prime minister. I do not think anyone doubts that Lapid is a candidate for the post, but somehow he has to utter the words in order for the incumbent to debate him. The back-story here is that Lapid has been trying to avoid a head-to-head fight and simply position himself as part of a broad replace-Bibi block, and not appear too ambitious to get the job himself. He has implied that he would accept not being PM even if his party, Yesh Atid, were to be the biggest party in the anti-Likud bloc. All polls for many weeks have said the party will be the largest such party, but Lapid is not ruling out allowing someone else–presumably either New Hope leader Gideon Saar or even Bennett–to take the post if that is what is needed to replace Netanyahu. Regardless of declarations, isn’t Lapid clearly a PM candidate? Yes!
So I am genuinely puzzled by contention over which party leaders formally declare themselves to be candidate for prime minister and which ones do not. I wonder if questions of this sort come up often in other parliamentary campaigns.
(Note: I hope to get a pre-election preview post up as I have done for Israeli elections back to 2006 or so. The election is this coming Tuesday, so time is getting short. Anyway, for now, I guess this is the pre-election post. But watch for another possible one.)
* Bolivia once had a president who had finished third in the sole round of popular voting. This was possible because the rule at the time was the congress selected from the top three if none had a majority. Later the rule was changed to two-round popular majority.