The New Jersey plan proposed this.
They proposed this, because they wanted smaller states to have equal powers in the government with the larger states. The other plan proposed was the Virginia plan. They wanted the states to have votes proportional to the population. However, the small states didn't like this because they would have less power in the government.
Eventually, they decided on a compromise, with the Senate following the New Jersey plan of each state getting equal representation, and the House of Representatives following the Virginia plan of votes proportional to the population.
