The province has assigned its top mediator to help bring York University and its striking union closer together to try to end a labour dispute that has shut down the school since November.

Premier Dalton McGuinty says he has assigned mediator Reg Pearson to the file.

"I've asked him to go there and bang heads together," McGuinty told members of the media at a Wednesday news conference.

He said Pearson hasn't been given a deadline within which he must resolve the dispute, which has been ongoing since members of CUPE Local 3903 -- teaching assistants and contract faculty -- walked out Nov. 6.

On Tuesday, the union announced that 63 per cent of its membership had voted against accepting the university's most recent offer. The vote was called after the school asked the Ministry of Labour to step in to the process.

While the union continues to ask for the administration's participation in negotiations, York officials insist the two sides are far apart and say they have made their final offer, which includes a 10.7 per cent pay increase over three years.

York president Mamdouh Shoukri says the school has no intention of negotiating for the "sake of appearance."

About 50,000 students are out of class as they wait for an end to the strike. The union says its main outstanding issue in the dispute is job security for long-term contract faculty, who must apply to keep their jobs each term.

The provincial opposition has called for the legislature to force an end to the strike, but McGuinty maintains he'd like the two sides to come to an agreement through negotiation.

With files from The Canadian Press