Can withers be created in a mushroom biome?

I'm currently playing Minecraft on a factions server where raiding is a pretty common occurrence. Obsidian is an effective defense against tnt and creepers, but a wither can still get through it. Would building my next obsidian base in a mushroom biome force enemy players to spawn a wither far away and lure it to my base, or can one be built in a mushroom biome?