The 2019 federal election will likely be decided by voters in the suburbs in and around Toronto and Vancouver. What those voters might be thinking will be hinted at in two of the four federal byelections called for Dec. 11.

On Sunday, the Liberals announced that byelections would take place next month in the ridings of Battlefords–Lloydminster (Saskatchewan), Bonavista–Burin–Trinity (Newfoundland and Labrador), Scarborough–Agincourt (Ontario) and South Surrey–White Rock (British Columbia). 

The Liberals hold the two easternmost seats, while the Conservatives are the incumbents in the two westernmost ridings. 

Battlefords–Lloydminster and Bonavista–Burin–Trinity are not expected to be up for grabs.

The Conservatives' Gerry Ritz won the Saskatchewan riding by a margin of 43 points in 2015 and held it since he was first elected as a Reform MP in 1997. He announced his resignation in August.

The New Democrats last held a part of the riding between 1988 and 1997, but it has otherwise been a reliably safe seat for the Conservatives. Polls have suggested no significant movement in support in Saskatchewan since the 2015 federal election, so it is unlikely that anything is afoot that would flip Battlefords–Lloydminster out of Conservative hands — or even make it competitive.

Nobody won his or her riding in the 2015 election by a wider margin than Judy Foote did in Bonavista–Burin–Trinity, beating her Conservative rival by 71.7 points. She also announced her resignation in August.

The area has been split across multiple ridings in the past, but the region has been a safe one for the Liberals for most of its history in Confederation. Even in the disastrous campaign of 2011, the Liberals won all three of the ridings that share territory with Bonavista–Burin–Trinity.

Voting intentions have only gotten better for the Liberals in Newfoundland and Labrador. After taking 64.5 per cent of the vote in the province two years ago, the latest polls by MQO Research and Corporate Research Associates put it at 70 to 72 per cent, respectively.

South Surrey–White Rock was close in 2015

Dianne Watts, who resigned her South Surrey–White Rock seat to run for the leadership of the provincial B.C. Liberal Party in September, won her riding in a close contest in 2015. Under the banner of the Conservative Party, Watts captured 44 per cent of the vote against 41.5 per cent for the Liberals' Judy Higginbotham. Less than 1,500 votes separated the two.

Watts, a former mayor of Surrey, was a high profile candidate for the Conservatives two years ago. Her departure opens up an opportunity for Justin Trudeau's Liberals, who will likely present a high profile candidate of their own: Gordon Hogg, a former mayor of White Rock and the B.C. Liberal MLA for Surrey–White Rock from 1997 to 2017.

But the riding has not traditionally been friendly to the Liberals. It has been held by the Conservatives and its predecessor parties since 1974, and before then it was an NDP stronghold.

If the Liberals are able to wrestle the riding away from the Conservatives, it would be the second one this fall after their Lac-Saint-Jean byelection victory in October. The polls suggest the Conservatives' position in B.C. has worsened slightly since 2015. With Watts off the ballot and Hogg on it, that puts the riding into play.

The suburban vote in Scarborough–Agincourt

Scarborough–Agincourt is less likely to be on the bubble. The riding became vacant after the death of Liberal MP Arnold Chan in September.

Chan first won the riding in a 2014 byelection. He repeated his success in 2015, winning the seat by 14 points over the Conservatives. 

Scarborough–Agincourt has been held by the Liberals for nearly 30 years, but the Conservatives increased their vote share from 34 per cent in 2011, when the party won a majority government, to 38 per cent in 2015, when the party was returned to the opposition benches. It suggests the Conservatives cannot be discounted in the riding, particularly since polls indicate there has been a five-point swing between the Liberals and Conservatives in Ontario.

Nevertheless, Scarborough–Agincourt would not be high on the Conservatives' list for the 2019 federal election. But some of the ridings nearby would be. The results could provide some indication of the appeal of the Conservatives under Andrew Scheer in the Greater Toronto Area.

Poor options for NDP Leader Jagmeet Singh

NDP Leader Jagmeet Singh, who does not hold a seat in the House of Commons, has indicated he could be convinced to run in a riding in which he had a connection and that "makes sense."

Scarborough–Agincourt fits the bill on the first count, as Singh was born in Scarborough. But it would be a tough one for the former Ontario MPP.

Over the last 30 years, the NDP has not done better than 18 per cent in the riding and has been more likely to score under 10 per cent of the vote than above it. And while the riding has a significant visible minority population — the 2016 census puts it at 81 per cent — a majority of that population is of Chinese descent. Just 14 per cent of the riding is South Asian, a population in which Singh made significant inroads during the NDP leadership race.

Singh would have long odds to win the other three ridings as well, where he has no connection.

But the next federal election will be decided in ridings like South Surrey–White Rock and Scarborough–Agincourt, suburban ridings in Vancouver and Toronto with significant visible minority populations. The byelections could provide a foretaste of things to come.