Four byelections will take place across Canada in June, with a drop in popular support of more than 5 percent predicted to be a sign of trouble for major parties in the next federal election, according to Nik Nanos, Chief Data Scientist and founder of Nanos Research. Incumbent parties up or down 5 percent in polls can attribute this to the local campaign and voter turnout, but those beyond that threshold would indicate parties taking notice of trouble. The byelections come as a recent Nanos weekly tracking poll shows the Conservatives leading the Liberals by seven points nationally. The results cannot predict the next federal election, but will show “the mood on the ground” among core supporters.