Complex sentence: No provision for a deputy leader exists within the party constitution however, Liberal Democrat Members of Parliament can elect a deputy leader for their group in the House of Commons who is usually referred to as Deputy Leader of the Liberal Democrats.
Split into simpler sentences: No provision for a deputy leader exists within the party constitution however, Liberal Democrat Members of Parliament can elect a deputy leader for their group in the House of Commons. The holder of this post is usually referred to as Deputy Leader of the Liberal Democrats.