system
A chat on subreddit /r/NoStupidQuestions
human
Speakers are generally unanimously elected, with cross-party support in New Zealand's parliament. It's only been contested twice in history. The office of Speaker is then nominally neutral, tasked with running the House fairly to all members from all parties.
gpt
In the US, the Speaker decides all House business. They essentially decide what bills get voted on. 

As several republicans pointed out in recent tweets, picking the right Speaker means killing measures like DC statehood and allowing them to impeach the current president.