U.K. Prime Minister Theresa May is increasingly isolated as her demands to control all areas of policy alienate key colleagues, according to more than a dozen officials who worry tensions will undermine planning for Brexit.

Speaking anonymously because the subject is delicate, many of the government figures said an early period of goodwill toward May had given way to division and resentment, leading to policy mistakes that had to be hastily corrected. Much of that stems from the influence wielded by her joint chiefs-of-staff, Fiona Hill and Nick Timothy, the people said.

“This sounds like echoes of the end of the Thatcher era with ministers feeling it would be wrong to risk her wrath and stifling rational concerns,’’ said Richard Hayton, who teaches politics at the University of Leeds, England. It’s the feeling that the prime minister’s office “is too much in the bunker.”

May’s office said in a statement they didn’t “recognize this version of events,” and said the premier governs in an “inclusive manner.”

May is said to have been centralizing power more than her predecessor David Cameron while grappling with the most difficult task facing a British leader since the end of World War II. Not only must she extricate the country from the European Union, she needs to orchestrate a set of new trade deals at a time of economic danger, and rally the expertise and talent to pull it off.

May has little time to play with. The government must agree on its Brexit strategy within the next 14 weeks given that May has promised to initiate formal negotiations by the end of March.

Political Missteps

In a speech to the country’s top business group last month, May promised the U.K. would have the lowest corporate levies in the Group of 20 biggest industrialized and emerging economies. However, her comment was made without consulting the Treasury, which sets tax policy, even as it effectively committed the government to slashing corporate tax from 20 percent now to below the 15 percent President-elect Donald Trump has proposed.

Another example: Chancellor of the Exchequer Philip Hammond was criticized for failing to free up more money for seniors in his budget statement, but it was May’s two top aides who had opposed his proposal to release extra resources, people familiar with the situation said.

Back in October, May’s office had to apologize to Bank of England governor Mark Carney after she publicly criticized monetary policy, saying quantitative easing and low interest rates had “bad side effects.” Again, the Treasury was not consulted before the remarks.

Similar complaints about May’s office intervening were reported by officials across government policy areas, including those working on Brexit plans, health and social affairs.

Tight Ship

Hill and Timothy are said to deny top officials access to May, with even senior ministers and security chiefs finding it difficult to get past them to schedule a meeting with the premier, according to people familiar with the situation. Some are said to be so demoralized that they have given up trying to tell May the truth about what they think of her policies.

The officials fear the breakdown in trust between the premier’s office and other government ministries risks undermining the government’s ability to function when Brexit negotiations begin next year.

Still, however much May’s critics within the government dislike the combative style of her administration, many Conservatives are pleased that the party under her leadership has been 14 points ahead of the Labour opposition in recent polls. The exclusivity of May’s office “either indicates someone who is in trouble or someone who is obviously the only person for the job,’’ said Professor Tim Bale, from Queen Mary University of London. “I suspect it’s the latter.’’

Fear of Defeat

In private, ministers complain that the duo refused to allow even uncontroversial measures to be put to lawmakers because they are so afraid that the government could be defeated in a parliamentary vote. May has a small working majority in the lower house of parliament, which even a minor rebellion would wipe out.

The pair run the premier’s office in 10 Downing Street, holding sway over the operations of the entire government, and also worked with May at the Home Office between 2010 and 2015. They had both left the government by the time of the Brexit referendum in June but returned immediately to front-line politics to run May’s leadership campaign.

They are paid more than any other political advisers in the government, with salaries of 140,000 each per year ($172,000), compared to May’s 149,440 pounds, according to an official pay disclosure.

May’s official spokeswoman, Helen Bower, resigned this month after tensions with Hill, according to people familiar with the situation. In 2014, Hill was forced to step down as May’s aide in the Home Office after a row with the then-education secretary over how to tackle Islamist extremism in schools.