Patrick Cockburn: Saleh has followed the Mubarak route to alienating his people

There is always potential for violence in Yemen – the state is weak and one in five people pledge their allegiance to their tribe

It looks as if Yemen will be the third country in the Arab world after Tunisia and Egypt to see a change of regime. President Ali Abdullah Saleh of Yemen is visibly failing to cling on to power after 32 years in office.

Military commanders are defecting and sending their tanks to protect protesters in the streets of the capital, Sana'a. The massacre of demonstrators last Friday, in which 52 died and 250 were wounded, has not intimidated the opposition, and led to many senior officials defecting from the government.

As military units take different sides there is the possibility of civil war, though the Yemeni elite has long experience of defusing armed confrontations. President Saleh and his family could fight it out, and have placed tanks to protect the presidential palace, but the odds against them are stacking up. The "Friday Massacre" by pro-government snipers ended dialogue between the opposition and the state for several days, but this has been resumed and may lead to the President stepping down and being replaced, as in Egypt, by a military council. This would prepare for elections.

There is always the potential for violence because the 24 million Yemenis own an estimated 60 million weapons. The state is weak and at least a fifth of the population give their primary allegiance to their tribe. President Saleh has been reliant on boosting the power of the tribes over those of the state while creating a patronage system whereby all jobs are distributed according to political loyalty. The middle class is small compared to Tunisia and Egypt, and the proportion of university-educated graduates is low. The government has based its power on the tribes, while the opposition appears to be less dependent on tribal allegiances.

President Saleh's errors since demonstrations started in Yemen in early February are very similar to President Mubarak's. He offered change and said he would not run again for the presidency, but refused to step down. The regime used thugs to intimidate its opponents, and made the unlikely claim that it was the young demonstrators who were doing the shooting. It tried to get control of the local and foreign press. This culminated in the massacre last Friday that has probably ensured that President Saleh will go in the short rather than the long term.

President Saleh already faced a rebellion by the Houthi rebels in the north, secessionists in the south and al-Qa'ida cells. But the threat from the latter was exaggerated and manipulated by the government in order to extract aid and arms from the US.

Though the Yemeni government is autocratic and corrupt, it was never a police state to the same extent as Syria, Egypt or Tunisia. Government institutions have been weak, and their main failing has been failure to enforce the law and to provide security.

The economy suffers from high unemployment that has never improved sufficiently since the expulsion of Yemeni labourers from Saudi Arabia in 1990 after the invasion of Kuwait by Iraq. The country's limited oil reserves are also being depleted.