Martins was elected Mayor of the Village of Mineola, New York in 2003. During his mayoral tenure, Mineola's comprehensive master plan received a Smart Growth Award from Vision Long Island. He was named one of Long Island Business News' "Top 40 Under 40" in 2007.
2008 congressional campaign
In 2008, Martins ran for Congress against incumbent Democratic U.S. Representative Carolyn McCarthy. He was defeated.
Martins won election to the New York State Senate in 2010 as the representative for the Seventh Senate District. He defeated incumbent Democratic senator Craig M. Johnson by 451 votes. The election results were not certified until December 4, 2010. Johnson challenged the results and demanded a hand recount, but the New York Court of Appeals rejected his appeal on December 20, 2010. As Senator, Martins voted for the law creating New York State's property tax cap, voted to cut income taxes for middle-class homeowners, voted to repeal the MTA payroll tax for small businesses and schools, and supported repealing the MTA payroll tax in its entirety. He authored laws reducing busing costs for school districts; creating a truss notification system to improve safety for volunteer firefighters; and establishing a new state fund to help homeless veterans. Martins was highly critical of the New York State Education Department's implementation of the Common Core standards and called for the resignation of the State's Commissioner of Education for cancelling public forums on the issue with parents and teachers. While in the Senate, Martins repeatedly led Long Island's 31 state legislators in the number of bills sponsored that were ultimately passed by both houses of the State Legislature. In February 2016, Martins and Assemblywoman Michelle Schimel called for new state funding to support a comprehensive groundwater study for Long Island. An expanded version of their proposal was adopted by Governor Andrew Cuomo. Martins urged officials to take action in response to incidents of anti-Semitism against students and faculty on CUNY campuses and sponsored legislation that would prevent New York from entering into a state contract or investment with those who boycott Israel or other American allies. Martins served as Chairman of the State Senate's Labor Committee and was Co-Chair of the Senate's Task Force on Workforce Development. He previously chaired the Senate's Commerce, Economic Development and Small Business Committee and the Senate's Local Government Committee. Martins also served on the New York State Mandate Relief Council, which was created to help reduce costs for local governments and school districts by eliminating or reforming regulations. Martins was named one of the 50 Most Influential Long Islanders by the Long Island Press in 2011.
2016 congressional campaign
Martins ran in the 2016 Election to represent New York's 3rd Congressional District in the United States House of Representatives, and received the endorsement of the Republican Party, Conservative Party and the Independence Party. Martins was defeated by Democrat Thomas Suozzi in the general election. Suozzi won 53% of the vote to Martins' 47%.
2017 Nassau County Executive campaign
On April 26, 2017, Martins announced that he would run for Nassau County Executive. Martins received the GOP nomination for County Executive and was uncontested in the primary. Martins was defeated by the Democratic nominee, County Legislator Laura Curran, on November 7, 2017 election; Curran won 51% of the vote to Martins' 48%..
Personal life
As of 2018, Martins is a board member of the Henry Viscardi School. He is a recipient of the Melvin Jones Fellowship Award, the Lions Club's highest honor. He was honored as the 2012 Portuguese Man of the Year during Nassau County's first ever public event recognizing the Portuguese Community on Long Island. He and his wife, Paula, have four daughters.
