Justin Trudeau has announced he will step down after nine years as Canadian prime minister in the face of a mounting set of crises, but stay in office until a replacement party leader is chosen.

The "Trump factor" was a key element driving Trudeau's resignation, Chantal Da Silva said at NBC News. Incoming U.S. president Donald Trump has threatened to slap large tariffs on America's northern neighbor — and has frequently mused about making Canada America's "51st state.