CAIRO – Protesters flooded Cairo’s Tahrir Square on Friday in the second giant rally this week, angrily vowing to bring down a draft constitution approved by allies of President Mohammed Morsi, as Egypt appeared headed toward a volatile confrontation between the opposition and ruling Islamists.

The protests have highlighted an increasingly cohesive opposition leadership of prominent liberal and secular politicians trying to direct public anger against Morsi and the Islamists – a contrast to the leaderless youth uprising last year that toppled autocrat Hosni Mubarak.

The opposition announced plans for an intensified street campaign of protests and civil disobedience and even a possible march on Morsi’s presidential palace to prevent him from calling a nationwide referendum on the draft, which it must pass to come into effect. Top judges announced Friday they may refuse to monitor any referendum, rendering it invalid.