The York University strike is coming to a head.

For two and a half months, Canada’s third-largest university has been closed by a strike of CUPE local 3903, representing teaching assistants, graduate assistants, and adjunct faculty. The university has invoked a provision of Ontario labor law to force a one-time vote by the union membership on York’s latest proposal, and that vote will take place this Monday and Tuesday.

If all three units of the local approve the proposal in majority votes, the strike will end immediately and classes may resume as soon as the end of this week. If one or more units reject it, the strike will continue.

The two sides are wrangling over pay increases and job security, but some observers believe that the length of the new contract may be the crucial sticking point. Labor agreements at half a dozen other major Canadian universities expire in 2010, and the two-year deal CUPE is pushing for would allow them to join a multi-campus strike that year, should one develop. (The university is insisting on a three-year contract.)

There has been speculation that the provincial government may attempt to end the strike with back-to-work legislation, but the legislature is in recess until mid-February. The longer the strike goes, the more likely it is that an entire semester will have to be canceled, costing the university millions in lost tuition payments and throwing students’ progress toward degrees into disarray.

Voting begins tomorrow morning, and continues through early evening on Tuesday. Results will likely be announced that night. Check back here for more updates as the story continues to unfold.

January 20 Update: CUPE’s membership rejected the York offer by a decisive margin.