In the 2024 general election, Castro was the Democratic nominee for the third district of the
Northern Mariana Islands Senate against independent candidate and incumbent Senate President
Edith DeLeon Guerrero. Castro defeated DeLeon Guerrero receiving 5,178 votes to Deleon Guerrero's 4,210 votes. He was succeeded in Precinct 2 by Daniel Iwashita Aquino Jr, the former head of the Commonwealth Bureau of Military Affairs, who was elected alongside incumbent Paul Sablan. In July 2025, Castro proposed an amendment to substantially reduce the size of the Commonwealth Legislature, reducing the Senate to six members and the House to thirteen members. == References ==