Authorship is contested, but the line remains a clever description for safe Conservative ridings where "you can run a yellow dog and still win."
Despite their slump in the national polls, the Conservatives do still have "yellow dog" ridings. One of them is Macleod, in southern Alberta, which faithfully returned a Conservative in this week's by-election, with more than 68 per cent of the vote. The Conservatives won a similar result in a by-election in the rural Manitoba riding of Provencher last year. In 2012, another reliable seat, Durham, east of Toronto, returned a Conservative.
Apart from these kind of yellow dog seats, predominantly rural ridings, things are bordering on precarious for the Conservatives, to judge by recent by-elections. Yes, by-elections are uncertain weather vanes, since winds do change. Read too much into them at your peril. However, there are patterns.
In urban Canada, the Conservatives are in full-scale retreat. In Toronto, they went backward by 5 points in losing Scarborough-Agincourt and barely registered in Trinity-Spadina this week, echoing their results from Toronto Centre and Montreal's Bourassa last year. Shockingly, they nearly lost Calgary Centre in 2012, when candidate and former media personality Joan Crockatt just squeezed in, winning 36.9 per cent of votes to beat a well-known Liberal challenger by just four percentage points.
In two by-elections for ridings that used to be yellow dogs – Manitoba's Brandon-Souris (2013) and Alberta's Fort McMurray-Athabasca (2014) – the Conservatives' share of the vote dropped dramatically.
Taken as a whole, the Conservative vote has dropped an average of 13 percentage points in by-elections held since 2012, according to calculations by poll-watcher Éric Grenier for The Globe. If that swing was repeated in a general election, the Conservatives would be swept from office.
These by-elections have been almost as discouraging for the New Democrats. Despite presenting strong candidates, the NDP lost three inner-city ridings (Toronto Centre, Trinity Spadina and Bourassa) of the type the party needs to win.
But it was the Liberals who won them. The New Democrats did take Victoria in a 2012 by-election, but that's been it. Overall, the NDP's share of the popular vote declined by 10 points. A swing like that in a general election would drop them from the heady heights of Official Opposition to barren-lands third-party status.
These by-election results suggest (not predict) that the NDP's worst fear is unfolding: that voters other than confirmed New Democrats who want to be rid of the Conservatives see the Liberals as the best vehicle.
This drift would strike New Democrats as unfair. NDP Leader Thomas Mulcair has shone in the House of Commons. He is serious, thoughtful and tough, just as an opposition leader should be. Yet somehow, he has lacked a certain je ne sais quoi in connecting with voters, whereas his young, untried Liberal counterpart Justin Trudeau sparks a buzz in most rooms he enters.
That buzz, and the party's sustained advantage in the polls, has helped with fundraising and the recruitment of strong candidates. Generally speaking, the Liberal candidates in the by-elections have been very good, even in ridings where they narrowly lost, such as Calgary Centre and Brandon-Souris.
On a national level, the Liberals' best strategic hope – one that seems thus far to be working – is to present themselves rather vaguely as the party of "change" and the best vehicle for the large majority of Canadians (60 per cent, according to Nanos Research) who could never see themselves voting for Prime Minister Stephen Harper's party.
The Conservatives are utterly convinced that the Trudeau buzz will fade when voters across the whole country confront the question not posed at by-election time: Who do you want running the country?
That question underpins the ongoing Conservative negative advertising campaign against Mr. Trudeau, whom they present as unready for prime time. All this, combined with large sums of public money shamelessly spent to promote Conservative policies, encourages the party to believe that Mr. Harper's "steady hands" will look comparatively better and better.
In the by-elections, the "steady hands" appeal has worked in yellow dog ridings but failed everywhere else. The oldest appeal in politics – time for a change – would appear to be resonating there, to the Liberals' benefit.