I think probably the drive belt will slip. If not the motor will
overheat, perhaps fatally. I don't think damage to the line is not so
likely, not enough power.

Why bother to 'think' about it? Avoid putting the added stress on the
fibers within the line. Indeed, there's not enough power in most washers to
destroy the line outright. But fray enough of the fibers within the strand
and find out later, when it's undoubtedly least convenient.