Priti Patel has formally apologised in parliament to Yvette Cooper after a Conservative activist was jailed for sending messages threatening to pay “crackheads” £100 to beat up the Labour MP.

Cooper used Home Office questions in the Commons to seek an apology after Joshua Spencer was jailed last week for nine weeks, and to ask why Tory MP Andrea Jenkyns gave Spencer a character reference at the court case.

The 25-year-old was arrested in April last year and stood for the Conservatives in May’s local elections.

He attended Cooper’s general election count in December as a representative of the Conservative party despite being under investigation by West Yorkshire police at the time.

Cooper told the home secretary that she had received an apology from the local Conservative association. She said: “But it is a concern to me that there been, thus far, no similar condemnation or sense of regret expressed by the national party. In a letter to me from the national chair in response to this issue, the strongest it said was: ‘Intimidating behaviour has no place in our politics.’”

Cooper said she was disappointed that Jenkyns had chosen to give a very positive character reference for this individual, without contacting her first.

Patel said: “Let me say this right now, on the floor of the house, that that is categorically unacceptable and wrong. There is no place for intimidation at all in public life. In terms of the national party response, she can take it from me, right now, that I am hugely apologetic for what she has had to put up with.”

On the character reference by Jenkyns, Patel said: “My understanding is that her comments were in support very much of giving the individual some help and support that that individual needed in terms of access to mental health.”

Spencer pleaded guilty in January to sending malicious messages about Cooper, a former work and pensions secretary who has been MP for Normanton, Pontefract and Castleford since 1997.

In a message sent last April to a man he met online, Spencer suggested Cooper should “pay” for trying to thwart a no-deal Brexit, after MPs voted to stop the UK leaving the EU on 29 March 2019 as planned.

He wrote: “We should have left [with] no deal on the 29th before the whore Yvette got her hands on to it and voted to revoke democracy. She will pay. I’m already organising … to hurt her. Amazing what crackheads will do for £100. I’m going to get her beat up.”