Four federal byelections on Monday will test just how much of a comeback the Liberals have staged under the leadership of Justin Trudeau.
While they're not necessarily harbingers of what's to come in next year's general election, the two Toronto ridings and two Alberta ridings up for grabs will send some important signals.
The Liberals' all-out effort to steal the downtown Toronto riding of Trinity-Spadina from the NDP will give some indication about who's got the edge in the battle for opposition supremacy.
The Conservative attempt to snatch Toronto's Scarborough-Agincourt from the Liberals may also provide evidence of whether the party's attacks on Trudeau and his support for marijuana legalization are effective.
And how the Liberals perform in Fort McMurray-Athabasca, Alberta's oil sands heartland, will signal whether there's signs of life for the Grits in what has been a political wasteland.
The Conservatives are expected to easily hold onto the other Alberta riding, Macleod.