Catalonia's parliament is to convene on 12 March to appoint a new regional president.
The jailed separatist, Jordi Sanchez is the only candidate being put forward.
Mr Sanchez, who is the former head of the pro-independence civil group, the Catalan National Assembly, is considered to have little chance of taking up the post since he remains in custody pending accusations of sedition over last year's secession bid.
His name was put forward after the former Catalan president Carles Puigdemont withdrew last week.
Mr Puigdemont had initially been picked as the candidate to lead the region again after December’s regional polls but he remains in exile in Belgium.
Today, Mr Sanchez's lawyers asked the Supreme Court, which is overseeing his case, to let him out of prison to go to parliament next week for the official appointment.
But even if a judge allows him out, he is not assured of getting enough votes to secure the position.
He has the support of two separatist groupings which together have 66 votes out of 135.
The small, separatist CUP party, which has four seats, has refused to back him and will abstain.
Of the 66 though, Mr Puigdemont and another separatist lawmaker are in Belgium, which means that in theory they cannot take part in parliamentary votes, reducing the number of lawmakers in support of Mr Sanchez to 64.
The parties that are against independence have a total of 65 votes combined, which means they could block Mr Sanchez's appointment.
The separatists' push for independence plunged Spain into political crisis last year.
The Spanish government imposed direct rule over the region on 27 October after the Catalan parliament unilaterally declared independence.
Direct rule is due to last until the region elects a new president.
Madrid has vowed to resist any breakaway of the region from Spain.