About 9,000 college instructors, counsellors and librarians at 24 colleges were eligible to vote on the offer. (CBC)

Ontario college teachers have voted 51 per cent in favour of a proposed contract offer Wednesday, in results the union says are too close to call.

Lead college negotiator Rachael Donovan said instructors voted 51.25 per cent in favour of the deal and she's happy the unofficial results show many faculty saw this offer as fair and reasonable.

But the union said the 210-vote margin is too close to determine whether the offer has been accepted or rejected and notes that about 300 mail-in ballots remain to be counted.

Both sides will now await the official province-wide results that must be certified after a review by the Ontario Labour Relations Board.

It's unclear whether such a narrow vote could still lead to a strike, as the Ontario Public Service Employees Union said it will wait for final results before making a decision.

The instructors had already set a Feb. 17 strike date, but if the offer is ultimately rejected, a new strike date will be determined.

The vote was held by the Ontario Labour Relations Board after a request from the province's College Compensation and Appointments Council, which bargains on behalf of the 24 colleges. The colleges say the latest proposed contract, which includes a 5.9 per cent wage increase over three years, is their final offer.

The union that represents the 9,000 college instructors, counsellors and librarians recommends rejecting the offer. The Ontario Public Service Employees Union says it isn't satisfied with how the proposed contract addresses issues of workload and academic freedom.

A strike vote in January passed with the support of 57 per cent of those taking part.