Councillors have voted to shut Plas Madoc - despite opposition from 2,000 people - as part of a bid to cut spending by Â£45m over five years.
Protesters meeting on Thursday evening said they had not been given enough time to draw up alternative options.
The closure decision will still need approval from full council next week.
Committee members of the the Save Plas Madoc Leisure Centre Campaign urged people at the meeting to lobby their local councillors to voice concerns ahead of next week's vote.
The council has said the community could run the centre, but supporters said that even extending the deadline to the end of June for interested parties to come forward with propositions is too little notice.
The meeting at the Air Products Social Club, Acrefair, heard the campaign is consulting a barrister about the possibility of a judicial review of the council's decision.
A council report outlined opposition to the closure saying the leisure centre is regarded as a "valued resource that contributes towards health and wellbeing and a focal point for the local, deprived, community".
However, the report said the council faced big budget cuts and a Â£2m bill in maintenance costs at its leisure facilities, including Wrexham's town centre Waterworld swimming baths and gym.
Among those trying to save Plas Madoc include former Wales footballer Robbie Savage, who played five-a-side at the centre as a boy.

Staffordshire bull terrier Butch was labelled "dangerous" by Merseyside Police after he was found eating the corpse in 2015.
Officers said the 10-year-old dog, who had been trapped in the Liverpool flat for several days, presented a danger.
But a dog charity said Butch "did what was natural" and should be rehomed.
Judge Nigel Bird has now ordered a review of the seizure order and fairness of the court hearing.
The precise cause of Butch's owner's death remains unknown.
The force assessed whether the animal, which is not a banned breed, presented a danger to others and concluded it did.
A judge sitting at Liverpool Magistrates' Court agreed and ordered the dog's destruction in April 2016.
But the Senior Staffy Club said Butch was a "friendly dog" and sought permission for a judicial review at Manchester Civil Justice Centre earlier.
The charity said Butch's owner, who had been ill for some time, had been in the process of signing him over to the charity when he died.
Spokeswoman Kate Lee said a volunteer went to collect the dog from the property but did not get an answer.
She said it was distressing and unfortunate but Butch had done "what was natural for a dog" left without water or food for a number of days.
Ms Lee said: "We were there; we were ready to take the dog from the police and take him in our kennels and assess him and find him a suitable home.
"That's what should have happened."
The dog has been in police kennels since the owner's death in September 2015.
Merseyside Police said the Chief Constable has noted the court's decision.
A date for the review is yet to be set.

19 July 2016 Last updated at 14:39 BST
The suspected gunman was among the dead in the shooting near the Castle Swimming Pool in Spalding.
Lincolnshire Police, who were called to Pinchbeck Road at about 09:00 BST, said no shots were fired by their officers.
Those killed are believed to be two women and a man. Police said they were not looking for anyone else in connection with the incident.
Aerial footage shows the scene of the shooting.
About 150 people attended a meeting aimed at saving a leisure centre earmarked for closure in one of Wrexham's most deprived areas.
[NEXT_CONCEPT]
A dog sentenced to death after eating his owner's body has been given a stay of execution after a judge granted a judicial review.
[NEXT_CONCEPT]
Three people have died in a shooting near a swimming pool in Lincolnshire, police have said.