The BBC's MarkSimpson, in Dublin, says the "Yes" camp feared people, angry with continuing austerity measures, would vote against the treaty to punish the government.
But the BBC's Ireland correspondent MarkSimpson says its passage is not assured, given the country's political system is in a state of chaos and filled with bitterness.
The BBC's Ireland correspondent MarkSimpson says there were three-hour delays on some major routes out of the city on Monday, and the Dublin Dart train service was suspended.