The Taoiseach has appealed to every person in the country who believes that 'Ireland and Europe are better together' to help achieve a Yes vote in Friday's Lisbon Referendum.
Speaking at a press conference in Dublin, Mr Cowen said the vote is too important for people to stand on the sidelines.
Mr Cowen said that with five days to go, the campaign is going well, but is far from over. He described Friday as one of the most important votes in recent Irish history.
The Taoiseach claimed that as the campaign has progressed, the arguments of the No campaigns have been robustly and effectively dealt with.
He said the guarantees achieved have dealt with concerns on tax, neutrality, workers' rights, social protection and membership of the Commission, putting people in a position to feel easier about focusing on the real meaning of the Lisbon Treaty.
Mr Cowen added that the overwhelming evidence is that a Yes vote marks an essential step on the road to economic recovery.
Fine Gael leader Enda Kenny said he was confident, but not complacent about the result of Friday's Lisbon Treaty referendum.
He said his party would keep pushing for a Yes vote in the closing stages of the campaign.
Meanwhile, the final opinion poll of the Lisbon Referendum campaign shows the Yes side with a comfortable two to one majority among decided voters.
However, opponents of the Treaty have gained support in the last two weeks.
The Red C poll in today's Sunday Business Post shows that 55% say they will vote Yes, an increase of one point since the last Red C poll a fortnight ago, while 27% say they will vote No, an increase of two points.
18% are undecided and when they are excluded the Yes side has a two to one advantage.