NASA had only contracted for 15 Saturn V stacks, and in 1968 declined to start the second production run. Nixon only assumed office in 1969, at which point the only question was how many of the remaining ten stacks would fly as part of Apollo. Under Nixon the final three Apollo lunar missions were cancelled, with one of those Saturn V stacks being used for Skylab instead. But even if all three had flown to the moon stagnation was inevitable as NASA's focus had already been directed to the shuttle.