So even in bad circumstances popular support was not enough for them to become the majority party.
As for the Communists, they literally couldn't become the majority party even with Soviet tanks in Bucharest. They had to rig the elections to win the vote.
Yes, Romania eventually was put under the heel of both Nazi Germany and the Soviets, both had to use force to impose their control, but it looks to me like it was becoming a totalitarian state before that.
As I read more, King Carol II played off different factions within the country to advance his own dictatorial control of Romania. The 1938 coup seems to have been entirely internal and it may have been planned as early as 1937.
https://en.wikipedia.org/wiki/Carol_II_of_Romania
> Largely reflecting Carol's own political choices, the FRN was the last of several attempts to counter the popularity of the Iron Guard, itself a fascist and antisemitic movement.
The fact that Carol was able to seize power to such a degree was a problem. As was Carol itself. But I don't think it's a coincidence that his dictatorship coincided with the post-Great Depression period and the rise of Fascism and Nazism (i.e. external pressures). Or with the power struggles in the region between pro-French/British factions and pro-German ones.