Prior to joining electoral politics, Oprong was a pre-independence trade unionist, founding the
Kenya Quarry and Mines Workers Union (KQMWU). Oprong was among those who joined
Jaramogi Oginga Odinga to press for the release of Mzee
Jomo Kenyatta and others from detention before independence. At the independence elections in 1963, he was elected MP as part of the
Kenya African National Union (KANU) for the then Elgon West Constituency which was redrawn during his term into
Busia North Constituency. Then President Jomo Kenyatta appointed him as an assistant minister for Labour. After defecting from the KANU to join the Kenya People's Union (KPU), he was re-elected in 1966 in Busia North before the KPU party was outlawed in 1969. He ran for re-election in the 1969 general election but lost to
Lawrence Ojaamong. In 1974, Oprong is re-elected in Busia North. In 1979, Oprong runs for re-election but is defeated by
Stephen Echakara. In 1992, Oprong runs for election in
Amagoro constituency (renamed from Busia North in the
1988 boundary redistribution). In the 1997 election, Oprong lost his
primary for KANU and thus did not run for re-election. == Assassination attempt ==