Bangkok faces a growing crisis Saturday as tens, perhaps hundreds of thousands of frustrated “Red Shirt” supporters of the government and equal numbers of opponents descend on the city for mass rallies. Suthep Thaugsuban, the secretary general of the People’s Democratic Reform Committee, which has been attempting for five months to drive the democratically elected Pheu Thai government headed by caretaker Prime Minister Yingluck Shinawatra from power, said the coming events would be a final push in the campaign, which so far has left 24 dead and hundreds injured from scores of mysterious attacks.