Britain, Spain, France, Germany, Austria and Denmark all announced they recognize Guaido as the country's president, which came after embattled Venezuelan President Nicolas Maduro rejected calls for new elections.
On January 29, Washington slapped sanctions on the Venezuelan oil producer PDVSA and later transferred control of some of Venezuela's assets in United States banks to Guaido. In a statement, it accused them of submitting to a US "strategy to overthrow the legitimate government" and singled out Spain for acting "cowardly".
"Once more, they follow behind Washington", he added.
But he stopped short of breaking off diplomatic relations with the 16 European countries that recognized his rival Monday, unlike his swift move to cut off ties with the USA after it threw its support behind Guaido last month.
Eleven of the group's 14 members issued a joint statement calling for a peaceful change in government in Venezuela, without military intervention.
"If a military coup took place in Venezuela, Mr Pedro Sanchez, your hands will forever be stained with blood", he said. But for a variety of reasons, the government of President Vladimir Putin sees in Caracas an ally worth cultivating.
Mr. Marulanda said the recent Russian arrivals are special forces - Spetsnaz - who are being embedded among Venezuela's elite military units to better resist any US intervention or internal coup against Mr. Maduro.
Madrid, London, Paris, Berlin and several other European capitals on Monday also backed Guaido as interim president of Venezuela after Maduro refused to call a presidential election despite a European ultimatum.
In Europe, undeniably the most outspoken political leader against Maduro was Spanish Prime Minister Pedro Sanchez.
The Canadian Labour Congress (CLC), of which CUPE is a member, also issued a statement last week, warning of the dire effect of "international interference" in Venezuela's crisis.
Guaido is trying to force from power the socialist leader - labelled a dictator by the West and his Latin American neighbors after presiding over Venezuela's economic collapse - aiming to set up a transitional government and hold new presidential elections.
Earlier on Monday, Mr Guaido announced that he was working on creating an global aid coalition that would be delivered at three points yet to be determined.
In Sweden, Foreign Minister Margot Wallstrom said the election that brought Maduro to power was neither free nor fair and told Swedish SVT that Venezuelans "now must get new, free and fair elections instead".
Russian Federation and China, which have poured billions of dollars of investment and loans into Venezuela, are supporting Maduro in an extension of their geopolitical clashes with Washington.
"Why would you want a repeat of Vietnam in Latin America?"
Despite Guaido's pleas for their support, the armed forces - the country's key power - have remained loyal to Maduro, but the opposition leader has expressed confidence he will win over senior officers after a top air force general publicly sided with him on Saturday.
The United States last week imposed sanctions on Venezuelan state-owned oil firm PDVSA. "Their support for us has been fundamental", he said.
I ask the pope to make "his best effort to assist us on the path of dialogue", Maduro declared, "and I hope to receive a positive response".
"I don't accept ultimatums from anybody", Maduro told Spanish TV channel La Sexta.
All eyes are now on Venezuela's military, which has so far been Maduro's main pillar of support, but there have been signs of wavering in the ranks.