Rishi Sunak is under pressure to stop appointing Conservatives to key positions at the BBC after Richard Sharp’s resignation prompted criticism the party had undermined the broadcaster by flooding it with cronies. Sharp quit as BBC chair on Friday morning after an investigation concluded he had failed to disclose key information about his relationship with the former prime minister Boris Johnson when applying for the job in 2021. Sharp helped facilitate an £800,000 loan guarantee for Johnson when he was in the running to take over the broadcaster but did not tell the appointments panel. His resignation plunges the BBC into another period of uncertainty and mires the Tories in a further row over the behaviour of some its most senior members and appointees. It follows the recent resignation of Dominic Raab as deputy prime minister over bullying allegations and the sacking of Nadhim Zahawi as party chair over his tax affairs. But it also gives Sunak an unexpected opportunity to put his stamp on the broadcaster by appointing a new chair for a four-year term. Lucy Powell, the shadow culture secretary, said Sharp had caused “untold damage to the reputation of the BBC and seriously undermined its independence as a result of the Conservatives’ sleaze and cronyism”. She called on Sunak to run a “truly independent and robust” recruitment process for Sharp’s replacement, saying that only this could “restore the esteem of the BBC after his government has tarnished it so much”. Ed Vaizey, the Conservative peer and former culture minister, said the prime minister should make sure the next appointments process was “beyond reproach”. Peter Riddell, who was public appointments commissioner when Sharp was given the job, said Johnson had been “conflicted” during the appointments process. He called on Downing Street not to leak the name of a chosen successor over the coming months in an effort to put off other candidates. The report by the barrister Adam Heppinstall found Sharp had created a “potential perceived conflict of interest” by failing to tell an interview panel in late 2020 that he had discussed the BBC job with Johnson prior to sending in his application. Johnson went on to appoint Sharp to the job, months after friendly media outlets had been briefed that the former Goldman Sachs banker was Downing Street’s choice for the role. Sharp was also criticised for not disclosing a discussion with the head of the civil service during the recruitment process, at which he introduced a man who would later organise a £800,000 personal loan facility for Johnson. At this time the prime minister was struggling with his personal finances due to the costs of his divorce. It is still not known who ultimately loaned him the money. Sharp, a Tory donor who was previously Sunak’s boss at Goldman Sachs, quit on Friday morning. He concluded his continued presence at the BBC “may well be a distraction from the corporation’s good work”, while saying the lack of disclosure during the application process had been unintentional. Sharp had originally indicated he intended to fight to save his job, but he ended up resigning immediately after its publication. Tim Davie, the BBC director general, was spotted visiting Sharp’s house on Thursday afternoon, prompting speculation the chair was encouraged to quit. The investigation into Sharp’s appointment was particularly damning on the way the application process for the job was handled. Other candidates were put off from putting forward their names for the BBC job by the perception it was already lined up for Sharp, while at every stage it was made clear Downing Street wanted him to have the job. Sunak will have the opportunity to select his preferred candidate for BBC chair, with the hiring process – and the independence of the preferred candidate – likely to be subject to enormous external scrutiny. The government has the ability to appoint the chair of the BBC and several other directors, in addition to setting the amount of money it receives from the licence fee. One Downing Street source said they had been blindsided by Sharp’s resignation, given the indication he intended to fight on. “The PM really hasn’t been thinking about a successor to Sharp,” the source said. “He’s been focused on lots of other things, but not this.” Rather than immediately accept Sharp’s resignation, the government has asked him to remain in the role for two months so it can select an interim chair before starting the lengthy process of finding a full-time replacement. Under the terms of the BBC’s charter, the temporary chair has to be one of the seven non-executive directors who sit on the broadcaster’s governing board. They include public figures such as the former television presenter Muriel Gray, the financier Shumeet Banerji, the Welsh academic Elan Closs Stephens and the accountant Shirley Garrood. The most explosive option available to Sunak would be to appoint the former BBC journalist Robbie Gibb, who became Theresa May’s director of communications when she was prime minister. He was appointed to the BBC’s board as a director by Johnson’s government and has repeatedly criticised perceived anti-Brexit and anti-Tory bias in the corporation’s output. The simplest option would be to give the job to Damon Buffini, the deputy chair, who has been tasked with improving the BBC’s commercial performance. Another leading candidate is Nicholas Serota, the chair of Arts Council England. The government will then have to start the process of recruiting a full-time chair of the BBC to serve a fresh four-year term. This gives Sunak the unexpected opportunity of putting a Tory-backed appointee in charge of the BBC’s board until 2027, making it harder for a potential Labour government to shape the national broadcaster if it wins the next election. Sharp’s resignation comes at a troubled time for the broadcaster, which is facing a financial crisis after 13 years of cuts to its funding under a Conservative-led government. This week MPs criticised it for being too slow to move away from its traditional television and radio channels towards a digital future, saying the BBC risked being made irrelevant by rivals such as Netflix. Michelle Stanistreet, the general secretary of the National Union of Journalists, said Sharp “had lost the dressing room, he had lost the respect of senior figures in the broadcasting industry and besmirched the reputation of the BBC”. She urged the government to appoint a chair who would champion public service broadcasting. Labour has called for the recruitment process, which is likely to take most of the summer, to be transparent and independent. The party is already running its own panel to review the workings of the BBC, which met for the first time last week. It will come up with policy proposals on strengthening the BBC’s independence from government, especially when it comes to appointments. But top BBC appointments have always been in the hands of the government of the day, an influence that Labour may be loth to give up if it wins the next general election. In his resignation statement, Sharp said that “for all its complexities, successes, and occasional failings, the BBC is an incredible, dynamic, and world-beating creative force, unmatched anywhere”.