Environment Minister Phil Hogan has said that if there was a "credible alternative" to the €100 household charge then it would have been pursued.
Meanwhile scuffles have been reported between protesters opposing the charge and delegates entering the Fine Gael Ard Fheis in Dublin's Convention Centre today.
In a speech at the Ard Fheis Minister Hogan said the controversial charge was "a legacy left behind by the last Government that this Government had to deliver as part of our agreement with the Troika".
"If there was a credible alternative we would have pursued it," he added.
"The charge is a forerunner to an equitable valuation based property tax that will be introduced shortly, again as part of our international commitments under the EU/IMF Programme of Financial Support," Minister Hogan said.
"I have sought to protect the most vulnerable in society and have exempted large numbers of groups that are in greatest need."
Minister Hogan insisted that the monies generated by the charge will be ring-fenced to support local services for local people.
"This is about local communities committing to protect local services," he said.
"Despite the financial pressures, despite the newness of the concept and despite the time pressure that we have had to work within the Irish people have stepped up and registered in their hundreds of thousands.
"For that I thank them and acknowledge their genuine patriotism."
His comments came as official figures showed some 667,499 households having registered for the charge by 2pm today, with the deadline falling at midnight.
This includes those which have been fully processed, those which have been received but not yet processed and those which have registered for a waiver.
Meanwhile around 4,000 opponents to the charge were this afternoon taking part in a protest march which made its way to the Ard Fheis venue at Dublin's Convention Centre.
Tempers were reported to be fraying outside the venue with some scuffles between protesters and Fine Gael delegates entering the building.
Several delegates are reported to have been jostled and knocked to the ground by protesters.