York Region Transit and VIVA bus drivers are walking off the job as of midnight on Monday, as GO Transit negotiations continue.

The union, representing about 250 bus operators and maintenance staff at Miller Transit and more than 90 bus operators at First Student, announced the job action just after 6 p.m. on Sunday.

"We regret the inconvenience this causes for York Region transit users and we urge them to contact their councillors and mayors," said Ray Doyle, ATU Local 1587 president in a press release on Sunday.

"The politicians are the ones who are ultimately responsible for this mess and they are the ones who must fix it."

Talks continued on Sunday between Go Transit and management officials with both sides hopeful a deal can be reached, said Doyle.

Doyle said that the union is hopeful a deal can be reached before the strike deadline and that the union will continue to negotiate.

He said that an announcement will be made with plenty of time to let employees and customers know if there is a strike.

On Thursday, bus drivers serving Richmond Hill, Markham, Georgina, Aurora and Newmarket rejected their employer's contract offers.

GO Transit has warned that trains will still be operating but bus service could be cancelled on Monday.

On Go Transit's website the agency says that passengers with monthly passes with be reimbursed the amount spent relative to the duration of the disruption.

GO Transit is encouraging commuters to monitor the situation by:

• Visiting their website

• Calling 416-869-3200 or 1-888-438-6646

York Region Transit and its Viva service have told customers that staff members will make themselves available at terminals on Monday morning to help commuters plan alternate trips.

Several YRT/VIVA services may be affected, including:

• 51 YRT routes in Markham, Richmond Hill and Whitchurch-Stouffville, with some routes in the City of Vaughan.

• 29 YRT routes in Newmarket and Aurora with some routes in Richmond Hill, East Gwillimbury and Georgina

• Five Viva routes in Markham, Richmond Hill, Aurora, Newmarket and Vaughan

Maintenance workers contracted by YRT and Viva are also involved in the bargaining.

ATU Local 113 is representing maintenance workers and several Viva bus drivers.

York Region bus drivers are among the lowest paid in the Greater Toronto Area, according to a representative from ATU Local 113.