Complex sentence: Romney's ambitious plans for housing production increases for the poor, and for open housing to desegregate suburbs, were modestly successful but often thwarted by Nixon, and he left the administration at the start of Nixon's second term in 1973.
Split into simpler sentences: Romney's ambitious plans for housing production increases for the poor, and for open housing to desegregate suburbs, were modestly successful but often thwarted by Nixon. Romney left the administration at the start of Nixon's second term in 1973.