Chicago Teachers Union President Karen Lewis said Tuesday she opposes Chicago Public Schools’ proposal to stop paying a 7 percent pension benefit but did not rule out taking the offer to her members, despite CPS doing a poor job of explaining why it’s necessary.

The union is planning to discuss strategies around a possible teachers strike Wednesday evening at a scheduled meeting of its governing body.

The district has proposed phasing out the 7 percent contribution over this year and next. Sources have told the Sun-Times the board would also consider a three-year wind down as well to spread out the pain.

The union leader had said last January, before taking an offer to her members she considered “serious,” that she was open to pension concessions as part of negotiations. But on Monday, CPS’ first day of classes, she said her members aren’t interested in any contract that cuts their pay or their schools.

“That’s something we’d have to talk about with our members, if they’re willing to do that,” Lewis said of eliminating the pension benefit.

“I don’t understand why it has to be phased out. Nobody’s made a clear argument for me to why that is, when we’re looking at coming out of a contract with less money than we started. So as far as I’m concerned, I don’t know how you take that to your members and say, ‘Oh, what do you think?’ And then expect me to look with a straight face to my members and say, ‘Wait a minute, my paycheck is going to be lower,’ ” Lewis said at CTU headquarters, flanked by vice president Jesse Sharkey.

Her comments could add more complications to contract talks between CPS and CTU that have dragged on for nearly two years without an end in sight. She has said her members will not work another full school year without a new deal.

The broke Board of Education has asked teachers to start paying 7 percent of their employee contribution toward pensions, a cost the district agreed decades ago to bear instead of paying raises. In exchange, the district offered modest raises over three years of its proposed four-year contract that it says will benefit teachers by the final year.

“The pension pickup is obviously something that is very costly to the district,” CEO Forrest Claypool said outside a newly reopened Dyett high school Tuesday, declining to explain why it’d cost more than paying out cash raises. He called the pickups unusual for unions in Chicago, saying most city employees pay some 10 percent toward their own retirements, even if conceding that many Illinois school districts pay them.

But he added that the scenario on the table isn’t set in stone.

“We’ve said repeatedly that we’re open to any ideas that CTU has to culminate a deal,” Claypool said. “We’re flexible on different terms that can be worked through across the basic foundation of the January agreement that we reached with president Lewis and her team. I’m hoping these next few weeks will be productive.”

“We’ve made a lot of progress this year but the district remains in very serious financial straits, and so the key is to give the teachers as generous a raise as we possibly can within the resources the district has,” he said.

District leaders have also said they’ve conceded on a number of quality-of-life agreements teachers have long requested, such as reducing paperwork for school staffers and giving them more autonomy over grading.

Sharkey said those can only go so far when CPS has already made so many cuts.

“We say, ‘Oh we’ve got a promise for you on lesson planning.’ Big whoop, if the public schools themselves are completely eviscerated and undermined,” he said. “What our membership says is, you know, ‘If you’re going to offer us a contract that’s a pretty crappy contract, it’s less than inflation in which people take pay cuts, at the very least promise to defend the public schools, promise that you’re not going to layoff staff and you’re going to have fewer and fewer people teaching more and more kids, warehousing kids.

“People don’t want to see their schools cut, that’s the big one, and the Board can’t promise that.”