Query: When did Kerry become a Senator?
Context: After receiving his J.D. from Boston College Law School, Kerry worked in Massachusetts as an Assistant District Attorney. He served as Lieutenant Governor of Massachusetts under Michael Dukakis from 1983 to 1985 and was elected to the U.S. Senate in 1984 and was sworn in the following January. On the Senate Foreign Relations Committee, he led a series of hearings from 1987 to 1989 which were a precursor to the Iran–Contra affair.