Politicians have an obligation to support democracy

Support for fptp by the mainstream parties is a form of 'partyism' whereby these parties do not feel the need to extend their democratic privilege to other parties. It means they discriminate against the other parties. This is not such a contradiction for the left because they are generally seen as inclusive parties which means that even though they are discriminating against other parties in their support for fptp they are still inclusive. We might not expect a communist party to be democratic. A right-wing party on the other hand would understand that to seek parliamentary power without a democratic mandate is illegitimate. It is more offensive and inconsistent for the right to support fptp and reject democracy than the left. If the right are more liberal-minded then it doesn't make sense for them to seek office without seeking a democratic mandate. Communists assume no one is antagonistic (and would not worry about being democratically accountable) but people on the right generally do not hold that view... they would not seek office without being democratically accountable. The illegitimacy of fptp is more of a threat to the position of the right because the left do not concern themselves with being accountable. (The left see themselves as benign so they have less reason to justify their power.) The right (unlike the left) have a problem if they seek to justify their power on the basis of a fptp election. Political parties have an obligation not to be partyist (anti-democracy) and to favour proportional representation.