THE stand-off between the Spanish and the Catalan governments has entered a new stage.

Catalan president Carles Puigdemont has, in effect, announced independence - but postponed making it official.

This leaves room for a dialogue, which the Spanish Government will not join until the Catalans renounce independence.

Instead, it will on Saturday invoke Article 155 of the Spanish constitution, allowing it to take over the work of the devolved administration.

This provision has never been used and it is not clear how it will work.

Contrary to some commentary, it does not allow it to suspend the Catalan institutions themselves.

That was tried in 1934, to disastrous effect in the years leading up to the Civil War using powers in the constitution of the Second Republic.

Instead, in a few words, Article 155 provides that, where an autonomous government fails in its constitutional or legal obligations or threatens the national interests of Spain, the central government can take measures to ensure that those obligations are met and the general interest protected.

This is likely to mean giving directions to Catalan government services and taking over finance.

Most controversially, it could mean placing the Catalan police under the orders of Madrid.

All this requires is an absolute majority in the Spanish Senate, which the governing Popular Party has.

It is likely, however, to seek to carry the opposition Socialists with it and they favour a minimal intervention.

While Article 155 does not appear to allow the Spanish Government to call new elections in Catalonia, they have used the threat to try and force Puigdemont to do so.

He is unlikely to do so as his own party could do very badly, while the more radical nationalists would probably advance.

Successive elections and unofficial referendums have merely demonstrated that Catalans are divided on the question.

The invocation of Article 115 will trigger further mobilization and harden attitudes in Catalonia, while the insistence of Puigdemont that he has a mandate for independence will continue to infuriate Madrid.

The Socialist Party has argued that a reform of the Spanish Constitution is necessary to allow Catalonia greater recognition as a national reality together with more autonomy, although they stop well short of accepting the idea of an independence referendum.

The Popular Party has indicated that it may be amenable to discussing this.

The Basque Nationalist Party, having moved away for independence, are seeking a new accommodation within Spain.

So a resolution is available in the form of a looser, federal and differentiated Spain.

That, however, is for the long term and provides little hope for an exit from the present confrontation.

Michael Keating is Professor of Politics at the University of Aberdeen and Director of the Centre on Constitutional Change