a big tent
1. noun A group, movement, or philosophy that appeals or caters to, or encompasses, the broadest and most diverse amount of members possible. We pride our church on being something of a big tent, welcoming any and all who wish to join us. The party is trying to establish itself as a big tent, broadening its aims to appeal to the widest amount of voters possible.
2. adjective Appealing or catering to, or encompassing, the broadest and most diverse amount of members possible. Often hyphenated. In my opinion, their big-tent politics, while reaching more people, dilute the potency of their goals.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a big tent
A big tent is a group such as a political party that includes people with a wide range of opinions. They argue that the party should be a big tent, whose only qualification for membership should be a common belief in lower taxes and smaller government.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012