"To control the chamber" means to have the power or influence over the decision-making process within a particular governing body or organization. Full definition
The district is considered a swing seat and will likely be pivotal in deciding which party controls the chamber in 2017. (nystateofpolitics.com)
That's because the party needs a showing at the polls that hasn't been achieved in over a half - century to guarantee its members will control the chamber in 2017. (politico.com)
All seven candidates are running races that could decide which party controls the chamber next year. (nystateofpolitics.com)