SoftBank has put off plans for a London Initial Public Offering of Arm due to political turmoil in the UK government. This cast doubt on Britain’s future as the home of the Cambridge-based tech company. Boris Johnson, the UK prime minister, has personally lobbyed Masayoshi Son, SoftBank’s billionaire founder, to get at least a partial listing of the chip designer on London Stock Exchange.

Johnson’s government fell earlier this month and investment minister Lord Gerry Grimstone, as well as digital minister Chris Philp, resigned. Both had played key roles in discussions with the Japanese tech investor. According to people familiar with the talks, SoftBank has halted discussions regarding a UK listing for Arm. An Arm IPO would mark one of the largest tech flotations ever for London’s market. SoftBank could be able to go for a simpler US listing than Son originally preferred, thanks to the political turmoil.

According to sources, SoftBank was meeting officials and executives from exchanges about an unusual dual primary listing. This would have allowed it to simultaneously trade in New York and London.

This approach has been avoided by companies in the past due to the complexity and cost of simultaneously running two IPOs. Prospectus and other regulatory requirements for the US Securities and Exchange Commission and UK’s Financial Conduct Authority are required. According to two people who are familiar with SoftBank’s thinking, work on the London IPO side had been effectively halted within SoftBank.

One of these people said that a London listing is less likely than in the past. SoftBank bankers have said that SoftBank only considered selling shares in London due to the strong incentives provided by the UK government. Officials were given the task of negotiating the conditions for listing and promised to make Arm a national leader for British technology. London has been criticized for not being attractive to fast-growing businesses due to the possibility of higher valuations and deeper investor cash pools in the US.

According to someone familiar with government efforts, officials from the Department for Digital, Culture, Media and Sport and the Department for Business, Energy and Industrial Strategy continue to work on a package that will attract an Arm listing. They said that Philp was being replaced by Matt Warman, a former journalist and digital minister. SoftBank was also being convinced by executives at the London Stock Exchange. After Johnson’s announcement that he would be making way for a new prime Minister in the next weeks, Grimstone quit the government and led the lobbying efforts. He even flew to Tokyo to meet Son.

A City executive involved in lobbying efforts asked the government for more efforts. He stated that “the main ministers who are dealing with SoftBank had left.” Gerry was crucial.” Whitehall is also concerned that SoftBank may not feel obliged to sell Arm to London markets as the political pressures will subside over the summer months. One official said that Gerry is gone now it was a concern. “There’s a vacuum right now, and [SoftBank] never wanted to do it anyway; all they wanted was to play ball with UK government.” According to a source close to the talks, work on a dual-jurisdiction Arm IPO has reached a “mature stage” in the UK.

This unusual route could allow Arm to get index inclusion in both countries, which would increase the number of investors in the company and speed up its entry into the FTSE 100. Arm was told by a UK banker that dual listing is not unreasonable. “Arm used trade at a premium in the UK, and it had an enormous fan club when it was first listed over here. That group has never seen anything more attractive to buy. Imagine Son being the first company to be in both the FTSE 100 & the S&P 500. To attract wealthy older investors who are more familiar with the company’s early days, one option is to offer a retail offering as part of the IPO.

SoftBank recently invested in PrimaryBid. This platform allows retail investors to purchase into IPOs. One person suggested that this could be used to attract private investors to the UK company. PrimaryBid worked last year on a British member’s offering for Soho House’s US listing. Anand Sambasivan is the chief executive of PrimaryBid. He stated that a retail offer in the UK would recognize Arm’s unique British history, be well-received by investors, and be a win for the nation.

SoftBank and Arm refused to comment. Arm previously stated that it intended to keep its headquarters within the UK regardless of where it lists. The UK government didn’t immediately respond to a request.