Lambert was a member of the
New Jersey General Assembly from 1780 to 1785, and in 1788. He was a member of the
New Jersey Legislative Council from 1790 to 1804, and served as vice president from 1801 to 1804. Lambert was the Acting
Governor of New Jersey in 1802 and 1803, serving in 1802 due to a deadlocked vote in the gubernatorial election. He was elected as a
Democratic-Republican to the
Ninth United States Congress and
Tenth United States Congress, serving in office from March 4, 1805, to March 3, 1809. Lambert was elected to the
United States Senate and served a single term, from March 4, 1809, to March 3, 1815. On June 17, 1812, he voted against war with Britain. What is now the city of
Lambertville, New Jersey was named in his honor in 1814 when the community's first post office was established. Lambert owned and managed a
plantation. He was an avid reader, and was known for owning one of the most esteemed libraries in Hunterdon County, == Death ==