It's blue enough as far as presidential elections are concerned. With the electoral college system, you only need a slim majority voting Democrat, and Canada as 51st would reliably provide that. Even where Congress is concerned, it would become significantly harder to elect a Republican majority I think, though there would be more of a battle there.

The logical candidate for 51st state, of course, is Puerto Rico, and the GOP is not super-enthused about them either. It's hard to say how they would vote long-term, but they certainly have a strong and well-justified hatred for Trump.