Frank Underwood tried to work with him to get a spending bill through the Republican-controlled Senate. Their agreement broke down under pressure from Tea Party member Senator Curtis Haas, and Mendoza ordered the Republican senators to leave the Senate chamber during a quorum call, in order that Frank (who was President of the Senate as part of his role as Vice President) would not be able to take a vote on the bill. However, the Senate Minority Leader moved to compel the attendance of absent senators, which motion was easily passed due to the lack of Republicans in the chamber, and the sergeant-at-arms was instructed to arrest any absent Senators and escort them back to the Senate chamber. Consequently, Mendoza and his fellow Republicans were handcuffed and carried into the chamber "under protest" by Capitol Police so that a quorum would be present. The amendment was then passed by the Senate.
He appears later in the season, alongside Curtis Haas once again. Both are seen addressing a crowd of reporters on the situation regarding the Chinese money laundering scandal surrounding President Garrett Walker and call for his impeachment. They are later confronted by Senator Michael Kern, who by Frank's subtle prompting, informs them he has five Democratic votes in the Senate willing to impeach, including himself. They ask if he'd want to join them in appearing before the media and he responds by saying, "the country could use some bipartisanship in action."
Mendoza meets with Claire Underwood regarding her desire to be appointed as the Ambassador to the U.N. He claimed he would not openly oppose her, but at a later hearing antagonizes her with questions. Claire's reaction, claiming the US Military is 'irrelevant' to the hypothetical situation prevents her from attaining the role. Mendoza later reveals he only antagonized her to see how she reacted under pressure, testing her suitability for the role.
Mendoza is named as a strong contender for the Republican nomination for the 2016 Presidential Election by both Bob Birch and Claire, but Mendoza neither confirms or denies this to Frank Underwood. It is revealed later in the season that amidst a scandal of accepting undeclared payments for speeches, Mendoza had resigned. He was replaced as Senate Majority Leader by Senator Henry Mitchell.
- Hector Mendoza is portrayed by Benito Martinez is Seasons 2 and 3 of House of Cards.
- As seen in season 3, Hector Mendoza has a portrait of Ronald Reagan hung in his office. Specifically one in which he is wearing a cowboy hat.
- This is later mentioned by Frank when introducing him to Viktor Petrov.
- Hector Mendoza's Senate seat was held by John McCain in real-life.