Mabon ap Gwynfor, Plaid Cymru spokesperson for Clwyd South, said:
"Campaigners for the new Trust aiming to re-open Plas Madoc were given new hope last week when reports emerged that Labour councillors were going to back a £100,000 support package for the centre.
"This was in response to a motion submitted by Wrexham Independent Group, who campaigned against the closure of Plas Madoc, to fund Splash Community Trust with £50,000 to allow them to re-open the centre.
"So today's Executive Board could have undone some of the damage caused when the Labour-run council closed the centre in April. However, instead of new hope we had a new kick in the teeth as Labour, Tory and Democratic Independents lined up to vote down the amendment.
"All the talk of Labour backing was just bluff and bluster for the newspapers."
Councillor David A Bithell, Leader of Wrexham Independent Group, said:
"Despite considerable opposition and public protests and a motion to give the trust a life line - Labour are trying to give Plas Madoc a slow death. Deferring this to September 9th is another nail in the coffin, time is running out before the bulldozers move in !
"Labour and the Democratic Independents have let people down in Wrexham South and I hope that the voters will remember who closed Plas Madoc come the next election."