Given the task definition and input, reply with output. Given a passage and a question, find the answer to the question based on the passage. The answer should consist of only one word that lies in the span of only one of the sentences in the passage.

Paragraph: Elections to the United States Senate will be held November 6 , 2018 , with 33 of the 100 seats in the Senate being contested in regular elections . The winners will serve six - year terms from January 3 , 2019 , to January 3 , 2025 . Currently , Democrats have 23 seats up for election along with 2 independents who caucus with them . Republicans have 8 seats up for election . Two of the Republican seats are open as a result of Tennessee Senator Bob Corker 's and Arizona Senator Jeff Flake 's pending retirements . The seats up for election in 2018 were last up for election in 2012 , although some seats may have special elections if incumbents die or resign , as has already happened in Alabama and Minnesota . After the 2016 elections , some state election officials are trying to upgrade voting systems in time for this election .
Question: how many senate seats are up for election in 2018


33