This is a problem that the upper house in a bicameral system is supposed to solve. The lower house is assigned to smaller regions, with one representative per

This is a problem that the upper house in a bicameral system is supposed to solve. The lower house is assigned to smaller regions, with one representative per region. If every single region has party X at 20% of the vote (and always lower than another candidate), then every region has individually voted for someone else. The upper house is assigned to larger regions, with multiple representatives per region. You don't have to have to come first to have at least one representative in the upper house. As an example, in my state (victoria, australia) we have 12 senators. They take the total vote count and figure out how many votes you need to get a senator. They take the party with the most votes, give them a senator, and remove X votes. Rinse, repeat. The last senator (or sometimes two) is usually decided by preference flows. At 20% of the vote, you'll be looking at 2/12 senators, and possibly a third depending on preference flow. The problems in the US and the UK are these: the fewer senators you have per region, the harder it is to be representative, so in the US with only 2 upper house members per region there's not much scope for variation; and in the UK, the upper house isn't elected anyway. Mid-sized minorities just can't get representation (mathematically, at least) in either of those two upper houses.