Ahdut HaAvoda
In 1948, Lamdan joined Mapam. In 1949, she was elected to Israel's First Knesset. She was re-elected in 1951, but on 20 January 1953, she and David Livschitz broke away from the party to form the Faction independent of Ahdut HaAvoda (several other Mapam MKs had broken away to re-establish Ahdut HaAvoda). On 13 January 1954 Lamdan and Livschitz joined Mapai.