Boeing has withdrawn a contract offer that would have given striking workers 30% raises over four years after talks broke down.

The manufacturer said that it had boosted its offer for union workers for take-home pay and retirement benefits during two days of negotiations.

“Unfortunately, the union did not seriously consider our proposals. Instead, the union made non-negotiable demands far in excess of what can be accepted if we are to remain competitive as a business,” Boeing said in a prepared statement. “Given that position, further negotiations do not make sense at this point and our offer has been withdrawn.”