Partly as a result of this appeal, the head of state instituted the Presidential Commission for the Study of the Communist Dictatorship in Romania, which was headed by historian Vladimir Tismăneanu, and a report which the president read in Parliament. During the subsequent controversy, criticism of Băsescu and the report was notably voiced by the opposition groups: the Social Democrats, the Conservative Party and the Greater Romania Party. In February 2007, as parliamentary forces voted in favor of an impeachment referendum against Băsescu, Rebengiuc joined Tismăneanu and 48 other intellectuals in signing an open letter condemning the move. They argued that such a reaction had been made possible by "the concerted attacks of those who felt shaken their business, their impunity, the possibility of perpetuating the post-communist oligarchic state." Warning that, together with the break-up of the Justice and Truth Alliance, this kind of reaction had fermented "a political crisis", they also supported Băsescu's stated goals of stamping out corruption and granting the public opening the archives of the communist secret police, the Securitate. Other signatories of the letter included Gabriel Liiceanu, Sorin Ilieşiu, Mircea Mihăieş, Dan C. Mihăilescu, Mircea Cărtărescu, Magda Cârneci, Horia-Roman Patapievici, Şerban Rădulescu-Zoner, Andrei Oişteanu, Ruxandra Cesereanu, Dan Perjovschi, Alexandru Zub, Virgil Nemoianu, Adriana Babeţi, Livius Ciocârlie, Andrei Cornea, Sabina Fati, Florin Gabrea, Andrei Pippidi, Dan Tapalagă, Sever Voinescu, Florin Ţurcanu, Hannelore Baier and Traian Ungureanu.