Monday's federal byelections are not expected to change the seat count in the House of Commons as all are being held in safe ridings for the Liberals and Conservatives.

But there are still things to watch for as voters cast ballots in five ridings across the country that will test the popularity of a midterm government and the impact of the ongoing Conservative and NDP leadership races.

The byelections are being held in Ottawa–Vanier and Markham–Thornhill in Ontario, Calgary Midnapore, Calgary Heritage and in the riding of Saint-Laurent on the island of Montreal. They will fill the vacancies left by Mauril Bélanger, John McCallum, Jason Kenney, Stephen Harper and Stéphane Dion, respectively.

The two southern Calgary ridings have been Conservative strongholds since their creation — the Liberals last won the area in 1968, when few people lived within the modern boundaries. The three other ridings have been safe Liberal seats for years. Ottawa–Vanier, depending on how one defines the boundaries through history, has voted for the party in every election since 1887.

The margins in the 2015 federal election in these five seats were wide, ranging from McCallum's 23-point win in Markham–Thornhill to Kenney's 44-point victory in Calgary Midnapore.

Incumbent parties winning fundraising war

There have been no polls published for any of the five byelections. Regional numbers from national polls provide little indication the incumbent parties are in any danger of losing their seats.

But national polls — which might sample 10 or fewer people from a given riding — can only say so much. However, fundraising data from 2016, the most recent available numbers from Elections Canada, also suggest the incumbent parties are well-positioned to hold on to their seats.

Based on those donations to the national parties reported with postal code information (which largely includes only contributions of $200 or more), the Conservatives raised the most money in 2016 in both Calgary Heritage and Calgary Midnapore, while the Liberals were the fundraising kings in Markham–Thornhill, Ottawa–Vanier and Saint-Laurent.

Data compiled by David McKie. (Natalie Holdway)

In all five of these ridings, the incumbent party raised at least 63 per cent of all contributions from at least 55 per cent of all contributors.

In Calgary Heritage, the Conservatives raised $140,800 compared to $48,700 for the Liberals, while in Calgary Midnapore the Conservatives took in $81,200 to $23,300 for the Liberals. The New Democrats raised just $5,350 in Calgary Heritage and $4,400 in Calgary Midnapore.

The Liberals raised $230,550 in Ottawa–Vanier against $90,600 for the Tories and $19,900 for the NDP. In Markham–Thornhill, the Liberal edge was $52,400 to $28,600 for the Conservatives and just $2,400 for the NDP.

In Saint-Laurent, the Liberals took in $27,300, while the Conservatives raised $8,900, the Bloc Québécois $3,200 and the NDP $1,100.

Not just about holding seats

The prospects of an upset in these five seats are dim. If any of the seats change hands, the defeated party will have serious questions to ask about what went wrong.

But in the more likely scenario where the Liberals hold their three seats and the Conservatives retain their two, the results will nevertheless answer some lingering political questions — and whether the parties show an increase or decrease in support may tell us something about where these parties are headed in the future.

The Liberals will be looking to see if the bruising nomination battles in Markham–Thornhill and St-Laurent, in which the party faced charges that it was interfering in favour of preferred candidates, will have any impact on their support.

The results in Markham–Thornhill may provide a clue as to the Liberals' support in the election-deciding Greater Toronto Area, while recent gains in Calgary will be tested in Kenney's and Harper's former ridings.

Opposition looks to pick up votes

The New Democrats, who did no better than 19 per cent in any of these five ridings in 2015, will be looking to avoid their catastrophic results in last year's Medicine Hat–Cardston–Warner byelection, in which the party took just one per cent of the vote in the southern Alberta riding and finished in fourth place behind the Christian Heritage Party.

Another poor showing could give the NDP's ongoing leadership race extra urgency — particularly if the Liberals repeat the byelection gains they made at the expense of the New Democrats in 2016.

The Conservative leadership race, meanwhile, is entering its final stages and the candidates' rhetoric has been heating up. The byelection results could provide some indication as to whether the extra attention is paying dividends, as well as providing some clarity to the disagreeing opinion polls that put the Conservatives either ahead of the Liberals or well back of their 2015 showing.

Answers will come after 9:30 p.m. ET on Monday, when the polls in the five ridings close and the vote counting begins.