There is growing anger and concern within the Labour party that the new Welsh first minister, Vaughan Gething, took £200,000 from a company whose owner was convicted of environmental crimes, with insiders warning it was critically undermining his authority and could cost the party votes at the general election. Gething, who made history when he became the first black leader of a European country in March, is facing growing calls to pay the money back and order an independent inquiry into the donations, which helped him secure a narrow victory in the race to replace Mark Drakeford. This week Plaid Cymru and the Welsh Tories led debates in the Senedd on the issue, and in the House of Commons the UK prime minister, Rishi Sunak, backed the calls for a independent investigation. But the most worrying development for Gething may be the tension within Labour that the party is being drawn into a sleazy Westminster-style donations scandal. Beth Winter, the Labour MP for Cynon Valley in south Wales, told the Guardian: “Restoring trust in politics is more important than ever. The ongoing furore around this donation casts a long shadow and there are upcoming elections to win. Clearing this up is in the interests not only of Vaughan Gething, but of Welsh Labour reconnecting with voters. An independent investigation is the only way this is going to get resolved.” Speaking in the Senedd, the former Labour deputy minister Lee Waters described the donation as “unjustifiable and wrong”. He said: “We are meant to be better than that. The reputation of politics, and politicians, seems to be lower than ever. We look to our leaders to model the behaviour we want to see, to reflect our nation.” A senior Labour figure, who asked not to be named, told the Guardian: “I think Welsh Labour is stunned by the whole thing … Everybody I know is aghast. Nothing like this had ever happened in Welsh politics.” The figure said the issue had become “insidiously poisonous” within the Senedd’s Labour group, where a majority supported Gething’s rival in the first minister race, Jeremy Miles. “I know Keir Starmer’s office is very concerned about it. I don’t see it going away. This is going to fester on and I honestly don’t know whether he [Gething] can survive.” Two £100,000 donations for Gething’s campaign came from a company called Dauson Environmental Group, whose director, David John Neal, was convicted of environmental crimes. Gething has ordered an internal review led by another former first minster, Carwyn Jones, while repeatedly emphasising that he has not broken any rules. But another insider said: “That’s exactly what David Cameron said about his involvement with Greensill. From a legalistic point of view, he may not have broken any rules but when you’re leader, you also have to have a certain moral authority. It isn’t just about being politically successful politically, it’s also having secure ethical standards.” Since he won the leadership race, Gething has taken part in three first minister’s questions sessions, and on each occasion was criticised for his donations. This week, questions focused not only on Dauson but on the taxi company Veezu, which also donated money to Gething’s campaign, after reports one of its drivers had refused to pick up a man with a guide dog. Gething said he was appalled by the case and was pleased that the company has removed the driver from its platform, but believed the public was more interested in the cost of living crisis than who had funded his campaign. A former Welsh minister said Labour members could not believe Gething’s lack of humility or acknowledgment that there was a problem: “In the short term Vaughan Gething may reckon he can tough it out, but the stench is not going away.” Plaid Cymru has a cooperation agreement with Labour but its leader, Rhun ap Iorwerth, said the issue risked poisoning Welsh politics. He said: “This isn’t the kind of politics we want in Wales. This leaves a very bad taste that needs to be cleared up.” Any money left over from Gething’s campaign is expected to be returned to the UK Labour party. Ap Iorwerth said: “The Labour party will have to come to a decision. Will they accept money that had come from a company whose boss had been found guilty of environmental crimes? Or if they pay it back because they judge that it’s the right thing to do, what does that tell us about the first minister’s judgment?” Andrew RT Davies, the leader of the Tories in Wales, compared the internal inquiry to the Soviet politburo “slapping themselves on the back and saying, ‘we’ve done a great job’”. Davies said the saga was stopping Labour getting on with the task of governing. He said: “We need to get this distraction off the table so the government can get on with the big-ticket job of dealing with health, education and economy.” The Welsh Lib Dem leader, Jane Dodds, said: “This episode has cast a dark shadow upon Welsh democracy. Politics has always been a dirty game where cash is often king, but this cannot carry on.” The donation row has particular resonance in some areas, including the Gwent Levels, a precious, protected landscape in south-east Wales, where Neal illegally dumped waste. Catherine Linstrum, the co-chair of Friends of the Gwent Levels, said: “This is depressing. Gething should give the money back and acknowledge the fact that he’s done the wrong thing.” Another of Dauson’s companies, Resources Management UK, faced action by Natural Resources Wales after complaints about the smell at a landfill site in Pembrokeshire. “It still stinks,” said a local resident, Sue Lewis. “I don’t think companies should be funding anybody. It looks like favours are being bought.” Will Hayward, the Welsh affairs editor for WalesOnline, said the saga had badly damaged Gething. “My impression is, if it wasn’t a matter of months before a general election, there would be moves against him from within the Labour group. The knives are absolutely out.” Laura McAllister, a professor of public policy at Cardiff University, said the £200,000 had made a critical difference in Gething’s campaign and he faced a difficult time – a split party at a time of squeezed finances, complicated by the impending end of the Plaid cooperation agreement. But she said the impending general election could help. “We know that discipline and a desire to retain power at all costs is what keeps Welsh Labour together however much they disapprove of the new FM’s actions. I suspect Gething’s future depends on whether he is regarded by those who matter as an electoral liability or an electoral asset,” McAllister said.