The Legislative branch consists of the bicameral Congress, made up of the Senate and the Chamber of Deputies. The Congress makes federal law, declares war, approves treaties and has the power of the purse and of impeachment, by which it can remove sitting members of the government. The Chamber of Deputies represents the people and has 257 voting members elected to a four-year term. Seats are apportioned among the provinces by population every tenth year.  ten provinces have just five deputies while the Buenos Aires Province, being the most populous one, has 70. The Chamber of Senators represents the provinces, has 72 members elected at-large to six-year terms, with each province having three seats; one third of Senate seats are up for election every other year. At least one-third of the candidates presented by the parties must be women.