Maybe, kind of sort of. This quickly gets into the particulars and is strategy dependent and also dependent on the other parties.
If you look at the passage of the Enabling Act in Weimar Germany, you see the Nazis seized control with the assistance of Zentrum and other centre and centre-right parties. The NSDP “only” had 33-43% support, considering the coercion around the March 1933 election, I expect the 43% figure is a little skewed. If there had been a Weimar version of the cordon sanitaire wrt the NSDP, would that have staved off the passage of the Enabling Acts? Maybe, but by that time you had Nazi paramilitary gangs engaging in open coercion and intimidation, with a dash of domestic terrorism. Of course the KDP (Communists) were behaving similarly, so you could arguably lump them in with the Nazis as destructive influences on democracy. Either way, when somewhere around a quarter to a third of your electorate doesn’t want your democracy to continue, you are in a troubled spot.
Looking at FPTP, I think the US right now offers a good insight into how a motivated group of the electorate with around 25% support could take over. The two big parties are essentially coalitions that are already locked in ahead of the election, and there have always been different (albeit less formally differentiated) camps within the parties. Alexandria Ocasio-Cortez is a Democrat, but she is also a member of the Democratic Socialists of America, Marie Gluesenkamp Perez is also a Democrat, but is not supported by the DSA. In a PR system they would be in different parties, that might often (depending on electoral outcomes) form a coalition. When you have something like the Tea Party and now the MAGA movement, you can see how one of these discreet groups within a larger party can essentially take it over, through the primary system. Liz Cheney, daughter of former Republican Vice-President has been pushed out by Donald’s MAGA supporters. Former Republican Presidential candidate Mitt Romney retires from politics, pushed out by the MAGAts. If you consider the population that actually votes in primaries, a much smaller, more organized movement within one of the two major parties potentially has a better chance of seizing control.
However 33% can win under FPTP while under PR they need 51% or the other parties to cooperate.
Maybe, kind of sort of. This quickly gets into the particulars and is strategy dependent and also dependent on the other parties.
If you look at the passage of the Enabling Act in Weimar Germany, you see the Nazis seized control with the assistance of Zentrum and other centre and centre-right parties. The NSDP “only” had 33-43% support, considering the coercion around the March 1933 election, I expect the 43% figure is a little skewed. If there had been a Weimar version of the cordon sanitaire wrt the NSDP, would that have staved off the passage of the Enabling Acts? Maybe, but by that time you had Nazi paramilitary gangs engaging in open coercion and intimidation, with a dash of domestic terrorism. Of course the KDP (Communists) were behaving similarly, so you could arguably lump them in with the Nazis as destructive influences on democracy. Either way, when somewhere around a quarter to a third of your electorate doesn’t want your democracy to continue, you are in a troubled spot.
Looking at FPTP, I think the US right now offers a good insight into how a motivated group of the electorate with around 25% support could take over. The two big parties are essentially coalitions that are already locked in ahead of the election, and there have always been different (albeit less formally differentiated) camps within the parties. Alexandria Ocasio-Cortez is a Democrat, but she is also a member of the Democratic Socialists of America, Marie Gluesenkamp Perez is also a Democrat, but is not supported by the DSA. In a PR system they would be in different parties, that might often (depending on electoral outcomes) form a coalition. When you have something like the Tea Party and now the MAGA movement, you can see how one of these discreet groups within a larger party can essentially take it over, through the primary system. Liz Cheney, daughter of former Republican Vice-President has been pushed out by Donald’s MAGA supporters. Former Republican Presidential candidate Mitt Romney retires from politics, pushed out by the MAGAts. If you consider the population that actually votes in primaries, a much smaller, more organized movement within one of the two major parties potentially has a better chance of seizing control.