``I think there will be a teachers strike.''

That's the blunt assessment of Ed Doherty, boss of the Boston Teachers Union.

Welcome back to school.

The BTU is now engaged in rancorous contract negotiations with the school department. As is always the case in these situations, a host of everyday issues is in dispute. But there is one that rises above the normal chatter of debate into the rarefied air of principle: hiring.

It is this issue that has pushed the Menino administration and the BTU into opposite camps, that has caused negotiators to walk away from the bargaining table, and that, for both sides, defines the future of public education in Boston.

The issue is straightforward enough: Who hires teachers?

Right now, seniority rules, with teachers in effect hiring themselves. Once they have three years experience, unassigned teachers can insist upon working at schools of their choosing, so long as a spot is not filled by a another tenured teacher. The wishes of the principal, other teachers, parents and the good of the school are irrelevant.

The school department is arguing for what it calls an open hiring system. Under that system, school-based hiring committees could select new teachers based on merit. The hiring committees consist of four people: two teachers (selected by other teachers at the school), a parent representative and the principal. The principal also has veto over any hiring decisions.

Reformers believe that winning on this issue is critical to any meaningful improvement in city schools. Chief among the advocates for change is a coalition of 33 Boston organizations called Boston United for Children. With a remarkably diverse membership that includes the NAACP, the Greater Boston Chamber of Commerce, the Black Ministerial Alliance and the Boston Municipal Research Bureau, Boston United is a political force to be reckoned with.

But, interestingly enough, the real impetus for reform has come from within. It is school principals who most adamantly have pushed hiring to the top of the agenda.

Recent reform efforts and the looming MCAS requirements mean that principals are now being measured by the success of their schools. If they have that responsibility, principals maintain, they also need the power to improve their schools - and chief amongst those powers is the right to hire the best teachers they can.

The teachers union couldn't disagree more. The BTU has long viewed seniority as a key employee protection, one that insulates teachers from favoritism. But, as those on both sides acknowledge, there are other ways aside from seniority to protect against such abuses.

In truth, the union's objections run far deeper. For years, teachers have been scapegoated for the failures of urban schools. Teachers are sick of it, and the hiring issue is their line in the sand.

Teachers are right when they argue that they have been unfairly attacked. Most teachers are caring, devoted and effective.

But by taking the position it has taken, the BTU simply feeds into the perception that, while teachers themselves are perhaps not to blame, teachers unions may well be. For example, angry at the slow pace of negotiations, the BTU is now engaged in its version of a slowdown, working to rule. As part of this, the BTU has instructed teachers not to make college recommendations for students. Tactics such as these seem cruel. They certainly don't do anything to improve the public's opinion of the teaching profession.

It's hard to argue with the notion that merit should drive hiring decisions. And it's also hard to argue with the idea that principals should have the right to form their own teams. Each school has its own culture, its own way of working. One or two bad hires, principals argue, can undermine an entire school.

So where does this go?

It may be that the BTU's talk of a strike is mere posturing, although Doherty says it is not. ``Teachers will not cave in on this,'' he says. Strikes by teachers are illegal under state law - the union can be fined and leaders can be jailed - but they have occurred in the past and easily can occur again.

There's strong political support for reform. An August survey conducted by Boston United for Children found 71 percent of city residents favor an open hiring system. More critically, 59 percent felt so strongly about it that they said it was worth the risk of a strike.

School department officials also feel strongly about the issue. But ultimately, the call will be made by Mayor Thomas Menino himself.

Menino came to office saying he wanted to be judged on the success or failure of the public schools. To date, as recent MCAS results make clear, improvement has been slow. Admittedly, going toe-to-toe with the BTU is fraught with risks. Residents today may say they would chance a strike, but if one actually occurs that sentiment could change.

Still, Menino is enormously popular. He has an accumulated reservoir of political capital that should allow him to take some risks.

This, it seems, is one worth taking.

Tom Keane writes weekly for the Boston Herald. He can be reached at tomkeane@tomkeane.com.