As Beverly Callaway stood at the edge of a strike line in South Park Thursday morning, she sounded mostly resolute. "The company needs to be more supportive of drivers," Callaway said. "We’re the ones that make this go every day.”

But when Callaway spoke about the students she has driven to school for the last two decades, her voice cracked. "You get attached. You really bond with them," Callaway said. "And it's something that I'm really missing right now."

Callaway, who has worked for the company First Student for 18 years, now drives students with special needs from Arbor Heights Elementary and Cleveland High School. He also trains new school bus drivers. Callaway, 58, said she currently has no health insurance through the company and recently unenrolled from a plan through the Affordable Care Act because she couldn't afford the $400 monthly cost.

First Student is the company Seattle Public Schools contracts with to drive about 12,000 students to school each day. The company is in a standoff with the union that represents drivers, Teamsters Local 174, over health insurance and pension for drivers. First Student says it has made a fair proposal to improve healthcare benefits; the union says the proposed plan comes with high premiums that are out of reach for drivers.

Drivers on the picket line Thursday described their mornings waking up before 5 am, days forming bonds with students on their routes, and, for some, daily commutes from cheaper suburbs into Seattle for work. Drivers, many of whom work fewer than 30 hours, also described either not qualifying for company health insurance or not being able to afford it. Some make too much to qualify for subsidies through the Affordable Care Act.

"I've been sick twice this winter and I haven't been able to seek good medical care early enough," Callaway said. "I've had to wait for either a little bit of extra money on my paycheck, scrimp and save, or let something go. It's pretty much devastating."

Currently, only drivers who work more than 30 hours a week qualify for health insurance through the company. But the union says more than 90 percent of drivers work fewer than 30 hours, leaving them without coverage. In two different contract offers this month, First Student has offered to expand insurance coverage to drivers who work under 30 hours and their families. But the union says the premiums would be too high. Teamsters spokesperson Jamie Fleming called the insurance plans "outrageously expensive."

"We're talking $1,700 a month for people who make $2,000 a month," Fleming said. First Student drivers do not receive pensions. A spokesperson for First Student said individual drivers would pay $36 to $45 per paycheck for insurance, but did not provide similar numbers for family coverage.

The company offered a deal in early January and another this week. Of the union members who voted on the first offer, 85 percent voted no. The latest offer this week was virtually unchanged from an earlier offer, Fleming said, so the union didn't bring it up for a membership vote.

In a statement, First Student Senior Director Chris Kemper called the company's offer "fair and equitable." The company said it offers drivers a 401(k) plan and $24 an hour. First Student said it would pay 80 percent of annual insurance premiums. "We care deeply about our drivers, and feel strongly that this deal reflects that," the statement said. "It’s extremely unfortunate that union leadership won’t let its members consider the deal on its merits."

Jasmine Hudson, who's 28 and has driven part-time for First Student for a year, said her four-year-old son qualifies for insurance through the Affordable Care Act but she doesn't have coverage for herself.

"We have to pay out of pocket and it's not fair to us if I'm working," said Hudson, who has asthma. "Even though I'm part-time, I need the benefits."

When driver Olivia Moore, 27, was diagnosed with skin cancer last fall, she had no health insurance. She avoided necessary tests and sought care from a sliding-scale clinic. "The bill is still kind of ridiculous," she said. "I'm in that weird gray area," Moore said, where she makes too much money to qualify for Obamacare but can't afford decent insurance elsewhere.

Moore, who has driven for First Student for about a year, said she's now cancer-free but has depression and doctors are still monitoring some spots on her skin. "It's the fear that I'm not going to have the luck slash resources I did to get it taken care of now if it's worse later," Moore said.

Driver Alex Bergstrom, 33, said he too recently "priced out" of subsidized health care, but can't afford other coverage. The lack of benefits drives workers away from the company, costing First Student money to train new hires that it could be investing in current employees, Bergstrom said. "I'm tired of this penny-pinching company treating us like cogs in a machine," Bergstrom said.

Drivers staged a one-day strike in November. This time, the union says drivers will strike until they reach a deal with the company. They announced the strike Tuesday to give parents advance notice that they would need to find alternative transportation.

First Student is offering eight hours of pay, $25 per diem, and meals to drivers who would work through the strike, according to drivers and the company. "More than 50" drivers showed up Thursday, according to a First Student spokesperson.

"All this money that they're willing to spend to fight against these drivers, if they would just invest that money in giving them healthcare," Fleming said. The union and company have not yet set the next date for negotiations.

Public school teachers and some members of the Seattle City Council have expressed solidarity with the drivers. "When public dollars go to contract businesses, it is imperative that we ensure we are taking care of the people who take care of our kiddos and this means a higher standard for wages and benefits," said Council Members Teresa Mosqueda, Lorena González, and Rob Johnson in a statement. (Mosqueda planned to make an appearance at the strike Thursday morning.)

"School bus drivers perform a very important social function in our city, ensuring students are transported safely to and from their schools. These same drivers are being shortchanged by First Student," Council Member Kshama Sawant wrote in a guest editorial. If the strike is still going, the Seattle Education Association has voted to stage a walkout in solidarity with the drivers on a Wednesday afternoon, after students have left, in order to not disrupt classes.

This post has been updated with additional comment from First Student.