have strength in numbers

To have an advantage because of the large number of people involved (in something). We should try to take action against the company with a class action lawsuit, rather than trying to sue them individually. We have strength in numbers, after all. Support for the nascent political party has grown like wildfire across the country, so they certainly have strength in numbers to push their agenda in Congress. Their makeshift army may consist largely of farmers and peasants, but don't discount them—they have strength in numbers.