LONDON (Reuters) – A small Northern Irish party which is keeping Britain’s government in power has concerns over Chancellor Philip Hammond, saying he is causing unnecessary division over Brexit, the Sunday Telegraph reported, citing sources in the party.

British Prime Minister Theresa May must warn Hammond he faces the sack unless he changes his approach to the UK’s departure from the European Union, unnamed senior parliamentary sources in the Democratic Unionist Party (DUP) told the newspaper.

Hammond has faced criticism from supporters of Brexit in his own party for what they say is his soft line with Brussels, and his reticence to put aside money for the possibility of “no deal” with the EU in Brexit negotiations.

But in a botched attempt to play down the party’s divisions, on Friday he described the European Union as the “enemy” in negotiations. He later said he regretted his choice of words.

“We are very concerned about Philip Hammond’s behaviour,” a DUP source told the Sunday Telegraph.

“It is evident to us that he is winding people up and causing unnecessary division within the Conservative Party at a crucial time in the Brexit negotiations.”

The DUP has only 10 lawmakers in Westminster, but May is dependent on its support after her decision to call an unexpected election this year backfired and lost her Conservative party its majority.

The Independent newspaper reported that the DUP were separately planning to vote with the opposition Labour party against the government over women’s state pensions, which the newspaper said left May at risk of a “humiliating defeat”.