Cristina Tzintzún Ramirez (born Cristina Costello; 1982) is an American labor organizer and writer. From August 12, 2019 until March 3, 2020 Tzintzún Ramirez was a potential challenger to incumbent United States Senator John Cornyn in the 2020 United States Senate election in Texas as part of a twelve-person Democratic primary, in which she placed third.