A former Nigerian governor who supervised President Muhammadu Buhari’s campaign finances has become the center of a corruption scandal that could taint Buhari’s anti-graft image. Babatunde Fashola allegedly misused finances while serving as governor of Lagos by rolling out grossly inflated contracts and leaving a massive debt of more than $2.1 billion to his successor, Akinwunmi Ambode, according to African Arguments via the Guardian.

Fashola, 52, has denied the allegations and called the claims against him “manipulated and unsubstantiated.” The former Lagos state governor was lauded by the U.K.’s Telegraph as “the man who tamed Nigeria’s most lawless city” and “a future president in the making.” During his two-year tenure, Fashola quickly became known for transforming Lagos city, Nigeria’s commercial capital, with far-reaching reforms that cleaned up crime and targeted corrupt authorities. He also took charge of Ebola operations in Lagos state, locating and isolating nearly 1,000 potentially infected people after Liberian diplomat Patrick Sawyer sparked the epidemic when he flew into Lagos airport.

In the run-up to the 2015 presidential elections, Buhari appointed the Lagos state governor as head of his presidential campaign’s finance committee and Fashola’s image apparently lent legitimacy to Buhari’s crusade on corruption. But when Fashola fulfilled his maximum term and left the governor’s office in May, allegations of financial and personal impropriety bubbled to the surface, according to African Arguments, a comment and analysis site run by Royal African Society from London and part of the Guardian African Network.

A report published by the Lagos state government in August revealed that Fashola spent 139 million Nigerian naira to drill two boreholes at the government secretariat in Lagos. The report said he also spent 78.3 million naira of taxpayer money to upgrade his official website and awarded a 640 million naira contract to German engineering firm Julius Berger for various construction projects at the Lagos House Marina, his official residence, according to Nigerian newspaper Punch.

A coalition of Nigerian anti-corruption organizations has petitioned for Fashola to be investigated by the Economic and Financial Crimes Commission over his “question expenditures,” Nigerian newspaper Premium Times reported in August. Fashola, a trained attorney, broke his silence in August and addressed the allegations against him in an op-ed for Nigerian newspaper Vanguard. He said Lagos state “always had debts” and ran deficit budgets in order to cater to the needs of its growing population. He also said the website upgrade was “being distorted” and was approved by the government.

“‘When you wrestle with a pig, the pig gets happy and you get dirty.’ This statement of profound wisdom informed my silence in the wake of manipulated and unsubstantiated allegations of wrongdoing recently being levelled against me,” the former Lagos governor wrote. “For those who still wish to remain in the mud, they should look in the mirror. For those who wish to throw mud at me, they should look at their own hands. As for me, I have moved on. My job is done.”

With links to Buhari’s campaign finances, the allegations against Fashola could smear the Nigerian president’s image and his efforts to tackle a culture of corruption and impunity left over from previous administrations, African Arguments reported.