Catalonia's jailed former vice-president has called for an end to the deadlock in parliament over the region's next president.
Oriol Junqueras said there is life in the pro-independence movement beyond ex-Catalan President Carles Puigdemont.
Mr Puigdemont insists he remains Catalonia's only legitimate leader, despite being in exile in Belgium.
Mr Junqueras was arrested in November 2017 for his role in October's declaration of independence from Spain.
He is the leader of the Republican Left of Catalonia (ERC), and was remanded in custody without bail on accusations of sedition, rebellion and misuse of public funds.
"The strength of a popular, democratic and non-violent movement resides above all in its capacity to broaden itself," Mr Junqueras explained in written answers to questions from the BBC he received from his lawyers on a recent visit to Estremera prison outside Madrid.
"It is the sum of many actors and social sectors, among them the leaders of parties. That is our strength."
Mr Puigdemont has demanded to be reinstated as president after his Together for Catalonia electoral list won 34 seats to the ERC's 32 in the elections of 21 December. But he remains in Belgium, facing the same charges as Mr Junqueras.
The situation has deadlocked the main pro-independence forces.
As long as no new government is formed in the region, direct rule from Madrid imposed last November will stay in force.
"Our priority is to implement the results of 21 December. To do that we need to get our government back in a very complex scenario," Mr Junqueras said.
"I am sure we will reach an agreement to form a government, and soon. It's a necessity."
On Tuesday the Catalan parliamentary speaker, the ERC's Roger Torrent, again delayed presenting a reform allowing Mr Puigdemont to be chosen as president without returning to Catalonia, where Spanish authorities would arrest him.
After almost six months of crisis since the controversial referendum, Mr Junqueras said the aims of politicians "must be always to improve people's lives, [and make] a fairer and freer state at the service of citizens.
"Most people don't feel that the state is serving them," he said.
On his own situation in jail for almost four months, Mr Junqueras said: "Prison is hard. And being in prison without having been convicted, when I am an elected MP who has always expressed himself democratically and peacefully, is surprising and something that would not happen in the UK."
Mr Junqueras, who is a devout Catholic and a father of two children, said he feared spending many years behind bars.
He accused Prime Minister Mariano Rajoy's Popular Party (PP) government of leaning on the judiciary for political purposes.
"If the state's attitude is one of punishment and vengeance, then prison could last a long time.
"There is a state attorney general chosen by the PP government. That attorney demands jail. And the judges grant it. Those are the objective facts.
"In any case, the important thing is not the individual's fate but that of the collective. History shows that democratic advances have often been preceded by prison and repression. Freedom has not been given away; it has always come at a price."
Mr Junqueras remains optimistic about the future of Catalonia as an independent country, "if that is what people want it to be.
"Democracy will advance and end up winning. Because otherwise, it would mean we were in an unstoppable process of democratic atrophy and authoritarianism, crushing the citizens' will."
Where are Catalonia's pro-independence politicians?
Twenty-eight Catalan politicians are being investigated by a judge from Spain's supreme court for their role in the referendum and subsequent declaration of independence.
Spain's constitutional court declared both the referendum and declaration illegal.
Four men currently remain in jail, having been refused bail: Mr Junqueras, Catalan ex-Interior Minister Joaquim Forn, and grassroots separatist leaders Jordi Sanchez and Jordi Cuixart.
Five politicians fled to Belgium, including Carles Puigdemont.
On Tuesday, Anna Gabriel of the Popular Unity (CUP) party said from Switzerland that she would not attend a supreme court hearing set for Wednesday.