As Trudeau shuffles his cabinet, which Liberals could use the profile boost at the ballot box?

Prime Minister Justin Trudeau is expected to shuffle his cabinet this week putting the final touches on the team he will lead into next year's federal election.

An informed source told CBC News late last week that the shuffle will come Wednesday.

Competence, regional representation and gender parity will play into any shuffle (although not necessarily in that order).But another question might come into play as well.

Does anyone not currently in cabinet need a promotion to have a shot at re-election in 2019?

It's common for governments to make some final adjustments before going into an election year. While most (if not all) of Trudeau's ministers are expected to run in the next election, ministers performing below expectationscould be moved out to make room for more deserving MPs.

A few extra seats also could be squeezed in around the cabinet table if the prime minister wants to give some of his people a higher profile without sacrificing a sitting minister.

There is an electoral advantage to being in cabinet. Last month's provincial election in Ontario is a case in point:of the seven Liberal MPPs who avoided getting swept aside by the party's historic defeat, six of them were in former Ontario premier Kathleen Wynne'soutgoing cabinet including Wynne herself.Theyheld on to their seats while other Liberal MPPswhowon by wider margins in the previous election fell by the wayside.

Cabinet minister stand-ins

The first place to look for possible new cabinet prospects is among the parliamentary secretariesMPs who assist full ministers and often take their place in question period when the minister is not present. It's a good audition for the big job. There are 35 parliamentary secretaries in the Liberal caucus, in addition to the 30 ministers around the cabinet table.

The results of the 2015 election offersome guide to which of these parliamentary secretaries might be in need of a little boost at the ballot box.

Five parliamentary secretarieswon their seats by less than five percentage points in 2015: Arif Virani (Multiculturalism), Celina Caesar-Chavannes (International Development), Kim Rudd (Natural Resources), Alaina Lockhart (Small Business and Tourism) and Jean Rioux (National Defence).

But the political landscape will be different in 2019. Rioux, for example, is the MP for the Quebec riding of Saint-Jean. It's a part of the province where either the New Democrats or the Bloc Qubcois would be expected to be the Liberals' main competitors, but both parties have seen their support drop in the province. That makes it unlikely Rioux will be in danger next year.

Who could be in trouble in 2019?

If we apply the change in support in each region of the country to the results of the last election in each riding, we can see which parliamentary secretaries might theoretically be facing defeat next year.

The Liberals have taken a hit in the polls in Ontario while the New Democrats have surged there. How much of this can be chalked up to the recent provincial campaign is unknown, and polling might return to more familiar patterns after the summer. But applying those shifts to their 2015 election results puts Virani, Caesar-Chavannes and Ruddbehind in their own ridings.

Addto that list parliamentary secretaries Marco Mendicino (Justice), Don Rusnak(Indigenous Services), Kate Young (Science) and Karen McCrimmon (Transport) all of whom won by reasonable margins in 2015 but could be in trouble now, based on the recent polls. In New Brunswick, where the Liberals have seen their support drop while the Conservatives' has increased, Lockhartalsowould be in dire straits.

A few other parliamentary secretaries would squeak by with wins of less than 10 points: Terry Beech (Fisheries and Oceans) in British Columbia, Matt DeCourcey (Foreign Affairs) and Serge Cormier (Immigration) in New Brunswick, Jol Lightbound (Finance) in Quebec and Omar Alghabra (Consular Affairs), Adam Vaughan (Housing and Urban Affairs) and Mark Holland (Public Safety) in Ontario.

A few factors could put extra pressure on some of these parliamentary secretaries.

The Conservatives look poised to do very well in the Quebec City region, which the centre-right Coalition Avenir Qubec party could sweep in the province's October election. That might put Lightbound and his Louis-Hbert seat in danger.

Disappointment over the collapse of the Energy East pipeline project might trouble Lockhart and DeCourcey in New Brunswick, while the Ontario NDP'srecent electoral breakthroughcould raise concerns over the chances of Toronto-area MPslike Virani and Vaughan, Young in London Westand KamalKhera (National Revenue) in Brampton West.

In British Columbia, anger over the government's purchase of the Kinder Morgan Trans Mountain pipeline could put the squeeze on Beech's seat in Burnaby NorthSeymour, andchip away at the wide 2015 victory margins of B.C. MPsPamela Goldsmith-Jones (International Trade) and Jonathan Wilkinson (Environment).

Delicate cabinet balancing act

But thereare only so many cabinet spots to go around. New Brunswick already has two ministers, which would make it difficult to add a third. Atlantic Canada as a whole is over-represented in cabinet compared to the region's population, while British Columbia and (especially) Alberta are under-represented.

Alberta has just one cabinet minister; its population should give it about three in a team of 30. But the Liberals only have one other MP who could be promoted to the post after MP Kent Hehrresigned.

That's Randy Boissonnaultin Edmonton Centre and he could use the help. He won his seat by just 2.2 percentage points in 2015 and provincewide polls in Alberta suggest that margin could get even tighter in 2019.

A few of these parliamentary secretaries have performed well in their roles and so will haveearned any promotions they might get. But if they do get bumped up to the big table, it will be hard to conclude that electoral considerations didn't also play some part in it.