New jersey delegates did not support the virginia plan because they thought

It gave too much power to the large states, is the right answer.

Explanation:

The Virginia Plan was proposed by the delegates of Virginia for a bicameral legislative division. This plan is also known by various other names such as the Randolph Plan and the Large-State Plan. This plan played a significant role in establishing the very notion of population-weighted representation.

The New Jersey delegates did not support this plan on the grounds that it gave too much power to the large states of the United States.