Stephen Brashear/Getty Images News The strike at Boeing (NYSE:BA) could \"go on for a while,\" union leader Jon Holden said in an NPR interview, and workers have \"the most leverage and the most power at the most opportune time that we've ever had in our history.\" \"And our members are expecting to use it, and they are,\" said the president of the International Association of Machinists and Aerospace Workers District 751. As many as 33,000 IAM members went on strike on Friday after overwhelmingly rejecting a new labor contract from Boeing (BA), which included a 25% wage hike over four years and a commitment to build its next airplane in the Seattle region instead of a non-union plant. \"I think that it was some of the best wage increases we negotiated,\" said Holden. \"It was some of the best job security that we negotiated.\" But workers wanted a 40% wage increase and the reinstatement of a defined benefit pension plan that was scrapped in 2014. \"A lot of the anger from our membership is coming from how they've been treated over the last 15, 20 years,\" Holden noted. Negotiations with the company are expected to resume this week, and Holden said workers are confident they can get their demands met.