St. Paul teachers and public school administrators say they agree on some of the key strategies necessary to help boost student achievement, including smaller class sizes, better ratios of support staff to students and increased access to preschool.

Yet the stall in contract negotiations after nine months of talks highlights the huge differences they have over how to accomplish those worthy goals, how much they cost and where the policies for them belong.

Teachers union leaders feel so strongly about non-wage issues that they have set a strike authorization vote. Last week, the St. Paul Federation of Teachers executive board decided that the union’s 3,200 members will vote Feb. 24 on whether to give their leaders permission to call a strike.

Teachers and administrators agree that a strike is not in the best interests of the district’s 38,000 students. That’s why they must pull out all the stops in the days ahead to avert a work stoppage.

Major obstacles in the talks include class size and staffing. Teachers want the contract to guarantee lower student-teacher ratios and higher numbers of support staff. They argue that to do their jobs effectively there must be smaller class sizes as well as more school nurses, librarians, social workers and counselors. And they say the district can raise the money and reallocate existing funds to make the necessary staffing changes.

Superintendent Valeria Silva and her negotiating team say the district cannot afford the $150 million it would take to make the changes. Nor will district leaders give up their managerial flexibility and be locked into specific class sizes when enrollment and state funding shifts can dramatically change budgets.

Hard staffing rules like those the teachers are demanding don’t belong in a contract. But they are items the two sides can and should work together to address. In fact, in the last contract, under a memorandum of agreement, district leaders agreed to a range of goals for class sizes. And in about 90 percent of the classrooms, they have lived up to those goals.

Not surprisingly, the administration and teachers differ dramatically on how much flexibility there is in the school’s $688 million budget. And the two sides remain far apart on pay issues. Teachers are seeking raises that would cost an additional $28 million over two years; the district is offering $16.5 million in increases.

With many St. Paul residents still struggling to recover from the Great Recession, the union risks losing credibility with taxpayers if it pushes its demands too far. There’s room for compromise on all of the issues on the table, but in the end the contract has to be affordable.

A prolonged strike would have a major impact on students, their families and the community. Students already have missed several days this year because of cold weather. No one wants to see their learning interrupted again.

According to district leaders, a walkout would cancel preschool classes and before- and after-school programs for the duration of a strike. Family summer plans could be disrupted if students have to attend school in June. A lengthy strike might affect state tests given in April, as well as high school graduation.

St. Paul is not the only district enduring contentious talks. About 50 percent of Minnesota’s 340 school districts have settled two-year agreements. But the state’s three largest districts — Anoka-Hennepin, Minneapolis and St. Paul — have all turned to mediators because they couldn’t make progress on their own. Teachers in Anoka-Hennepin chose to stop doing any work outside of school hours to protest stalled talks.

The last thing any of those districts needs is a work stoppage. Because St. Paul teachers have signaled the possibility of taking that step, it’s urgent that they return to the negotiating table and do what it takes to reach an agreement. If both sides truly want what’s best for kids, they’ll come up with a contract that keeps St. Paul students in school.