On candidates for political office Unelected political candidates for political office are difficult for Wikipedia editors to judge their notability, for several reasons. First, users are interested in knowing more about the subject, and there is a general trust that Wikipedia articles contain accurate and unbiased information. Second, candidates running for federal office (including a national parliament or congress usually receive a certain amount of press coverage (especially from "local" media). Third, there are some candidates who are perennial candidates, running campaigns across multiple election cycles.
On the flip side, many unelected candidates, especially, but not limited to third-party candidates, are notable only in the context of their run for office and would otherwise be considered a low profile individual. Also, the articles about candidate (especially those involving challengers) are prone to WP:Bias, as the editors of the articles may frequently be campaign supporters and are working in good faith to promote their candidate.
The other wrinkle is that not all countries have candidate-centric elections - and in most countries candidates run on a list produced by the political parties. The individual candidates on the list are less important to the election than the party's candidate for prime minister.
The challenge on judging the notability of an unelected candidate is to articulate a standard, when there are Wikipedia policies pointing toward greater inclusion and exclusion. At the end of the day, I think the current standard is the best one - unelected candidates should be redirected to the article about the election or a list of candidates. While this means that there will be debates about notability at XfD, this is better than the alternatives.
I believe that unelected candidates become notable when they receive significant international coverage of their campaign, if their campaign tactics receive in-depth coverage, or if they are covered in a fashion that personifies similar candidates.