Yemen's opposition parties said Sunday they are joining young protesters in their push to bring down the country's beleaguered president.
The announcement marked the second major setback in two days for President Ali Abdullah Saleh, a key U.S. ally in the fight against the al-Qaida terror network. On Saturday, two powerful chiefs from his own tribe abandoned him, and hundreds of thousands called for his ouster in the largest protests yet.
In recent weeks, Yemen has seen daily protests, inspired by successful uprisings in Egypt and Tunisia. The mainstream opposition parties had been reluctant to join, preferring a wait-and-see approach.
However, on Sunday they said they would hold rallies Tuesday to show solidarity with the protesters.
"We call on all the citizens to come out Tuesday and condemn the regime for its crimes," said the Joint Gathering, an umbrella organization for seven opposition parties, including socialist, moderate Islamic and nationalist factions.
The announcement is a blow to Saleh, who has been in power for 32 years, said Abdel Bari Taher, a Yemeni analyst. "If they join the people in the streets, they will swiftly decide the fate of the regime," he said.
Anti-government protests were held Sunday in cities across Yemen, including the capital of Sanaa, the city of Taiz and the port of Aden. In the eastern town of Malla, 18 protesters were injured in clashes with security forces, security officials said.
Security officials said Saleh dispatched army units, bolstered by tanks, to Aden to help security forces in putting down the protests. The officials spoke on condition of anonymity because they are not authorized to speak to the media.
On Saturday, Saleh appeared to be hardening his stance, after initially offering protesters to engage in dialogue and promising that the security forces would not use force against them. Yemeni TV quoted him as telling army commanders that the armed forces will not hesitate to "defend the security of the nation as well as the unity, freedom and democracy."
"We will fight to the last drop in our blood," he said.
Saleh's government had been weak even before the protests erupted. He was faced with growing al-Qaida activity and a separatist movement in the south. At the start of the protest wave, Saleh offered not to seek re-election in 2013, but was rebuffed by demonstrators.