Louise Boyd, president of the teachers' union, said the action was needed to address frustration over the district's failure to reach a settlement with the bargaining unit.
Neshaminy teachers have worked without a contract since 2008, as negotiations have toddled along, Boyd said.
"We have no other options," she said. "How long can we go without a contract and have the employers say to us they don't really care?"
Webb, though, insisted the district was caught in an economic crunch with a drop in school tax revenue due to lower property reassessments, decreased investment earnings, and the district's inability to raise taxes because state law makes it difficult to meet teacher demands.
"The reality is, the money's just not there," Webb said.
Teachers contend that with a little help from the reserve fund, a deal can be made, but Webb said he did not want to consider that.
Boyd said the union's last offer was a six-year contract with no raises in 2008 through 2011 and increases of 2.75 percent for the 2011-12 school year, and 3 and 3.25 percent the following two years.
The teachers would pay 8 percent of medical costs and shoulder bigger co-payments for medical costs and prescription drugs.
"We have made huge compromises in our health and welfare plan," Boyd said. "The funding is possible, but the board has never worked on trying to find a place where we can get an agreement."
Webb said the district was "willing to move." The district's teachers already are among the area's highest paid, earning an average of $80,000 to $81,000, with fully paid health benefits upon retirement.
It is unfair to expect taxpayers to absorb the cost of an enriched contract, he said.
"I am hearing overwhelmingly from parents: Stay the course, don't back down," Webb said.
Negotiating sessions are set for Thursday and Jan. 26.
Contact staff writer Bonnie L. Cook at 610-313-8232 or bcook@phillynews.com.