Northern Ireland Secretary Karen Bradley is “inept” and should feel “duty bound” to resign over Theresa May’s Brexit plan, the DUP’s Brexit spokesman has told HuffPost UK.

In a tirade which exposed the rift opening up between the Government and the Northern Irish party, MP Sammy Wilson accused Bradley of ignoring his concerns over the EU and failing to take her job “seriously”. 

Instead of meeting with him, Bradley has been pushing May’s deal “like a door to door salesman”, said Wilson.

Bradley was in Belfast with the PM on Tuesday trying to rally support behind May’s troubled deal.

The MP for East Antrim believes Bradley should follow the lead of Shailesh Vara, the former Northern Ireland minister who resigned when the Withdrawal Agreement was published.

“Shailesh Vara, who is a remainer, could have kept his head down and kept his ministerial post, but he read the deal and he was appalled,” said Wilson. 

“Now, let’s say I was Secretary of State for Scotland and I had seen a deal like this and it had the same impact on Scotland as this deal does on Northern Ireland, I would feel duty bound to resign.

“But Karen Bradley has not not even engaged with the substance of the complaints we have made.

“Instead, she is out selling the deal to businesses like a door to door salesman.”

It comes as the party threatens to stop propping up the government over the Prime Minister’s Brexit deal, which looks set to be voted down by MPs at a crunch vote on December 11. 

The PM and Bradley visited Belfast on Tuesday in a bid to drum up support. 

The DUP vehemently oppose the so-called Northern Irish backstop, which kicks in should the UK and EU fail to find a solution which avoids a hard border. 

The backstop means the whole of the UK will remain in the EU customs union, while Northern Ireland will have to follow single market rules.

Wilson was speaking after attending a meeting of the hardline faction of Tory MPs, the European Research Group (ERG), in Parliament on Tuesday night. 

He said he felt “total solidarity” with Tory MPs there and that had been assured “80 or 90″ Conservatives planned to vote against the deal. 

Asked why the PM brought forward the deal given the strength of opposition among DUP MPs, he said: “I just don’t think she has any political antennae. She has relied far, far too much on civil servants.

“She has been through two Brexit secretaries because she relied more on the civil servants.”

Asked if May had taken advice from Bradley, he said: “Karen Bradley is the last person I would take advice from. I don’t think she has much insight into Northern Ireland politics.

“She is regarded as pretty ineffectual.”

Bradley came in for heavy criticism after admitting in an interview with The House magazine that she “didn’t understand some of the deep-seated and deep-rooted issues that there are in Northern Ireland”. 

She added: “I didn’t understand things like when elections are fought, for example, in Northern Ireland – people who are nationalists don’t vote for unionist parties and vice versa.” 

Wilson said her words “show a lack of interest or insight into Northern Ireland”.

He added: “She handled the issue of getting the assembly back up and running in the most inept way.

“As secretary of state, she has not taken her duties seriously. She hasn’t looked at the impact of this deal on Northern Ireland, but she has been out selling it to businessmen.

“A lot of people say that she just isn’t interested in Northern Ireland – I’ve heard a lot of people say that.”