it's pretty much even when it comes to popular vote. the seat % that's very strongly in favor of the conservatives can be dramatically reduced if the liberals and ndp make a deal of removing the person that would likely comes place in second place to the benefits of the one that leads. it's what happened in france, the commies, socialists, greens, centrists and the "right" all conspired in the last election to give to the one person that leads the poll the chance to beat the pseudo far-right party of marine le pen by removing them from the list. we literaly saw the "right" of les republicains (the ex party of sarkozy) vote for a communist for exemple.
Canada