After a one-day strike in November, Seattle school bus drivers will begin a lengthier strike Thursday. Drivers plan to strike until they reach a deal with management at First Student, the bus company that contracts with Seattle Public Schools, according to their union, Teamsters Local 174.

The drivers say they are fighting for health insurance that is more affordable and covers their families. The company has defended its offer. This month, First Student took out a full-page ad in the Seattle Times addressed toward public school parents saying, "we care deeply about our students and we value our drivers."

Unions typically don't announce strikes in advance, but drivers want to warn parents who will need to arrange other ways of getting their kids to school, according to the Teamsters.

Since the November one-day strike, "First Student has not resolved any of the Unfair Labor Practices they had previously committed, including the unilateral implementation of the substandard healthcare plan," the union said in a statement.

Drivers rejected First Students last proposal from the company by 85 percent, according to the union. “85 percent is not a fluke," driver Star Lucas said in the statement. "It’s not a statistical error. It’s a strong statement to First Student that their proposal wasn’t good enough and they would need to bring more. We are not going to vote for a proposal that only takes care of us while our own children are left without decent healthcare."

Read the union's full statement here. Meanwhile, the 6,000-member Seattle Education Association, which represents teachers and other school staff, has promised a walkout in solidarity with the bus drivers.