TAFE teachers have been negotiating for a new workplace agreement for almost a year, but on Friday the Australian Education Union dramatically withdrew from the process and vowed to launch a campaign against the Labor state government.

The escalation comes two years after Premier Daniel Andrews promised to rebuild TAFE.

"We are on the brink of being betrayed," said Justin Mullaly???, the union's Victorian branch deputy secretary.

"You don't save TAFE by cutting teaching conditions, you save TAFE by respecting the workforce," he said.

One of the main sticking points is a government proposal to increase the workload of TAFE teachers.

Mr Mullaly said the government wanted to boost the annual teaching hours of TAFE educators by 20 per cent, from an average of 741 hours to 900 hours.

This excludes the hundreds of extra hours that Victoria's 6000 TAFE teachers already spend preparing for classes.

"This is an outrageous overreach in terms of teacher conditions," Mr Mullaly said.

The proposed changes could lead to staff cuts, he said, because TAFEs would expect fewer teachers to do more work.

The union has also slammed a government push to expand the hours that TAFE teachers can work without penalty rates.

Under current rules, TAFE teachers are paid standard rates if they work during a 10 hour period from 8am to 6pm. The government is pushing to expand this to 12 hours, according to Mr Mullaly.

"They are cutting penalty rates," he said. "Their position is at odds with federal Labor."

Another sore point is the $10,000 pay gap between Victorian and NSW TAFE teachers.

TAFE teachers in NSW receive a maximum salary of $95,569 compared to $85,613 in Victoria.

"If we are going to have a decent TAFE system the government needs to stands up and protect teachers. You don't get quality on the cheap."

TAFE teachers will meet with their local MPs and take to social media as part of their campaign.

It plans on recommence negotiations with the government once it has "shifted its position".

It has been a challenging era for TAFEs.

Enrolments are down by up to 40 per cent at some providers, and the union estimates that 3300 teachers have left the Victorian TAFE system in the past five years.

The situation has been blamed on a number of factors: the former Brumby government's decision to open the market to private training providers; private colleges tarnishing the sector; and the uncapping of university places, which has driven students away. Cuts to the sector were one of the reasons behind the former Coalition state government's one-term defeat.

The state government is investing $320 million in TAFEs through its "rescue fund".

A state government spokesman said the government valued the work of TAFE teachers and wanted the negotiations to continue "in good faith".

"This government's record investment in TAFE is already having an impact on the lives of tens of thousands of Victorians who wouldn't have been able to access training if it wasn't for the investment and reforms of the Andrews Labor Government," he said.