Tories are unusual

Which of the two fptp parties is more likely to resign their position and advocate pr? If we label the centre-left party as 'Labour' (Democrats in America...) and the centre-right party as the 'Tory' (Republicans in America...) party then we argue as follows: We assume that both parties are aware and willing to accept that pr would destroy their particular party whilst it might not destroy their cause. If the cause of the left is socialism and the cause of the right is freedom then it is obvious to the left (but not the right) that pr would produce freedom. The right are unaware that pr would produce freedom because they do not realise that votes for the left might become libertarian votes. The left however do realise that votes for the Tories will never become votes for the left. If someone is willing to vote Tory (or Republican) they will never switch to the left under pr... but the reverse is different ... it might be the case that votes for the 'left' under fptp would go to liberal parties under pr and the left are aware of this so we cannot expect them to switch because they know the problem. The right are less aware of the likelihood of pr leading to freedom because freedom is not a problem for them. They are less threatened by votes for Labour under fptp than the other way around. Labour know pr would be bad for them but the Tories aren't really aware of how much freedom pr would bring.