There's a scheduling problem to Collins' proposal.
The EU needs Lisbon in place by the end of October when a new commission must be appointed and it's not clear how to do that under Nice.
To avoid clashing with the budget, the referendum will have to held in early October.
To avoid clashing with the referendum, the Dáil can't be dissolved August-early October.
A GE in July would be very bad - too close to the disastrous locals and
FG's no confidence motion.
The Taoiseach doesn't have any real opportunities to dissolve the Dáil until the week before the budget, which would also be very bad.
FF don't have a good alternative to clinging to power until the economy picks up.