President Recep Tayyip Erdogan takes his new oath of office next week, cementing his legacy as Turkey’s most powerful leader in eight decades after a decisive electoral victory that has demoralized his opposition, now wracked with recriminations and infighting.

The swearing-in ceremony on July 9 effectively ends Turkey’s century of parliamentary democracy, ushering in a new executive presidential system following Erdogan’s re-election on June 24. He issued a decree on Wednesday that formalizes his authority to appoint the cabinet, which he is expected to announce after taking the oath.

As Erdogan prepares for the pageantry of his inauguration, to which he has invited foreign heads of state, opposition parties are trading blame over their failure to push him into a second round of voting and gain more seats in a concurrent parliamentary poll. The backbiting spells the end of the uncharacteristic unity they displayed before the vote, when the center-left Republican People’s Party (CHP) formed an electoral bloc with nationalists and Islamists to run for parliament.

The CHP’s Muharrem Ince had attracted record-size crowds to his marathon presidential campaign by railing against Erdogan’s perceived authoritarianism, but ultimately won less than a third of the vote. Following his defeat, he pledged to reach beyond the CHP to maintain a cohesive front, but first needs to boost support within his own 100-year-old party.