The historian Tony Judt has observed that Lübke's presidency, like the chancellorship of Kurt Georg Kiesinger, showed the "a glaring contradiction in the Bonn Republic's self-image" in view of their previous Nazi allegiances. Lübke's status as a one-time political prisoner under the National Socialists placed him in good stead, and it was not until 1966 that accusations started to be made by sources in the GDR that he had at the very least been aware of the use of slave labour on his projects; building plans bearing his signature and containing concentration camp barrack blocks were advanced as evidence of his complicity, but these were dismissed in the West as East German propaganda. Nevertheless, the potential scandal threatened to damage the office of the Federal President; in 1968 Lübke announced that he would resign the following year, his resignation taking effect three months before the scheduled end of his term of office.