Lewis was elected as a Democratic member of the New Jersey General Assembly from Hudson County in 1878. He was also a delegate to the 1880 Democratic National Convention and a member of the New Jersey Democratic State Committee in 1884, when he was active in the presidential campaign of Grover Cleveland. After the election of Cleveland, Lewis was appointed &lt;a href="United%20States%20Ambassador%20to%20Portugal"&gt;Minister Resident/Consul General to Portugal&lt;/a&gt; on April 2, 1885. He served until June 14, 1889, when he returned to Hoboken to resume his legal practice.