A spokesman from his Together for Catalonia political platform said that Puigdemont has gained the support of ERC separatists as well.
Mr Puigdemont, who is in self-imposed exile in Belgium, may either return and risk arrest or be sworn in from overseas.
Spanish Prime Minister Mariano Rajoy ordered the December 21 regional election under constitutional powers he invoked in October to dissolve the previous parliament after separatist lawmakers voted to declare Catalonia an independent republic.
But this was short-lived as Prime Minister Mariano Rajoy imposed direct rule on the semi-autonomous region, sacked its government, dissolved its parliament and called snap elections.More news: Jerry Richardson May Have Seen Last Game as Panthers Owner
He is in Belgium, however, and will be arrested if he comes back to Spain on charges of rebellion and sedition.
However, another issue is that although separatists have a majority, the rules of the Catalan assembly dictate that deputies can not delegate their vote and with Puigdemont in Belgium and Junqueras and other elected deputies either in jail or in exile and in theory unable to vote, that majority effectively vanishes.
"It's evident that for governing Catalonia you have to be in Catalonia, you can't do that via WhatsApp or as a hologram", said Ines Arrimadas, the leader of the anti-independence Ciutadans (Citizens) party.
Both parties have confirmed the deal but confusion remains about how the president will read his legally required installation speech to the Catalan Parliament on Wednesday without returning to Catalonia, where he is wanted by Spanish authorities. Insisting that such methods would be illegal, Mr Maillo said anything other than a traditional investiture - in which a president presented himself and his programme to parliament for a vote - would be "a real mockery, first of the Catalans, and then of the rest of the parliamentary groups". But a new president can form government with a simple majority in a second attempt.More news: European Court of Justice advisors say gay spouses have equal rights
Many of the Catalan political leaders were arrested on charges of sedition and rebellion after the independence declaration, with three still behind bars pending a trial, while Puigdemont, with four of his cabinet members, fled to Brussels. Spain has jailed other pro-separatist leaders involved in the independence push.
The plan may offer a way out of the chaos surrounding the formation of a new Catalan government at a time when many of its senior candidates are either in jail or facing prosecution.
"Madrid must be made to understand that what is needed is dialogue, negotiation and agreement on the future relationship we Catalans want to have with Spain - one based on respect, recognition, cooperation and equality", Puigdemont wrote.More news: Joe Arpaio Announces Senate Run