There are more than 2,700 taxi-drivers in Dublin and more than 1,000 outside the capital, with three organisations to represent them, but estimates of their membership vary considerably.
The National Taxi-Drivers' Union is believed to have between 2,200 and 2,500 members. The Irish Taxi-Drivers' Federation claims a membership of between 1,200 and 2,000.
The variations can be partly explained by overlapping membership and by volatility in representation in the sector.
Last year many of the more militant drivers left the existing organisations to join SIPTU, which is believed to have between 800 and 1,200 drivers.
While disagreements have emerged between the three bodies, and particularly between SIPTU drivers and the more established unions, all three have pledged to show a united front at tomorrow's meeting with Mr Molloy.