After the carnation revolution when the people where fed up with the colonial wars portugal went through the "PREC" (Processo Revolucionário Em Curso) which was a short era of societal reform that included nationalization of companies, the collectivization of farmland and the general growing of popularity of various worker-movements/ parties like the PCP (MLs) the PCTP (Maoists) and others like the UDP and some trots but nobody really gave a shit about them. It was a period of unlimited potential for a revolution and yet it failed to establish socialism in the country. From what i can tell, the main problems were disorganization within the parties themselves (especially the PCP which was the largest communist party and could've done much better than this) and the restraint to overthrow the state by violence. The PCP, one of, if not the, leading leftist party of this period refused to establish dominance by violent means...they know that the only way to establish a socialist government is with a revolution yet they seemed so paralysed during this time. On the 25 November of 1975, communits and socialists unsatisfied with the more "soccdem" way Portugal would take, decided to start a coup but failed as armed "moderates" stopped the attempt before it having any effect. Since then Portugal is just another european "soccdem (nuts)" country with a Neo-liberal government. The PCP still has seat in the portuguese parlament but is loosing relevance more and more while the "CHEGA" (a quasi fascist party with anti-immigration plans and tax cuts for rich and whatnot) party is gaining more popularity. Portugal could've become "europe's cuba" as Otelo Saraiva, a portuguese revolutionary put it. But at the end, fell victim to your average reddit-style "enlightened centrist" who wants a welfare system while conserving the neo-liberal mechanis.
It would have never been allowed by the US and the west.
https://www.workers.org/marcy/cd/samport/port/port02.htm
An interesting read and also gives a little more context. There was literally an US aircraft carrier at the gates of Lisbon, in case the country had the intention to become a communist one.
The guns and armor of the American aircraft carrier Saratoga stood out menacingly within sight of Commerce Square, opposite where most of the workers had assembled. This had to arouse the greatest indignation, not only from the demonstrators but from all Portuguese workers, especially when one remembers that the CP itself has stood out so long and undeviatingly against NATO. Yet one must wonder-how could the Armed Forces Movement agree to the participation of Portuguese naval units in an exercise which involved simulated bombings of central Portugal? And how can the Provisional government at this very late date still be a member of NATO, especially when the Pentagon has contemptuously barred the Portuguese armed forces from any so-called secret NATO material?