Leading Article: After uprising and murder

'Nothing ever happens in Mexico till it happens,' said President Porfirio Diaz as he went into exile at the start of the Mexican revolution in 1911. His words may seem cryptic, but everyone knew what he meant: once his own long hold on power was broken, events moved fast. So it has been with the party that emerged from the revolution that swept him out.

The Institutional Revolutionary Party (PRI) has enjoyed office uninterrupted since 1929. But its hold was visibly shaken by the rising this January in the southern province of Chiapas - and now once again events have gathered pace. With the assassination yesterday of Luis Donaldo Colosio, the PRI's candidate for the August presidential elections, the party faces a crisis.

The secret of its power has lain in its political skills and in the genuineness for many years of its claim to represent the post-revolutionary consensus. Successive leaders have tacked skilfully, claiming to represent the best of socialism and capitalism and rarely hesitating to play the anti- American card. Under the outgoing President, Carlos Salinas de Gortari, the government was seen by many who had not benefited from his free-market economic policies to have sold out to the gringos: the Zapatista rebels timed their uprising to coincide with the implementation of the North American Free Trade Area on 1 January.

Attention is now likely to focus on the man who successfully negotiated with them. Manuel Camacho Solis, a former mayor of Mexico City, did not hide his dismay when the presidential finger pointed at Mr Colosio as the PRI's candidate. Mr Camacho's success as a peacemaker was followed by hints that he might stand on an independent ticket, withdrawn a day before his rival was shot. If asked to take over the candidacy, he seems likely to accept. Given his popular touch, his liberalism and his belief in honest elections, he would probably give the PRI a better - and certainly more honest - result than the late Mr Colosio.

Economic liberalisation has greatly benefited Mexico's rapidly growing and increasingly influential middle classes. The message of the uprising in Chiapas was that the fruits of economic progress need to be more evenly shared if stability is to be maintained. The PRI will itself have to adapt to the changes that it has unleashed. A basis for reform is there in the electoral changes and economic measures agreed by Mr Camacho himself with the rebels.