Rishi Sunak tonight launched an attack on post-Brexit trade deals signed by Liz Truss as he tried to woo rural Tory members.

Sunak labelled the Australia and New Zealand trade deals negotiated by Truss when she was trade secretary as “one sided” during a hustings event in Exeter, while adding that the UK “shouldn’t be rushing to sign trade deals as quickly as possible”.

The two trade deals have been criticised by the farmers’ union for eliminating all trade barriers for Australian and New Zealand meat exporters.

Speaking in front of West Country Tory members, Sunak said: “It’s not rocket science … our farming communities are an incredibly important part of our country.”

It comes after fallen Tory leadership candidate Penny Morduant tonight endorsed Truss to lead the country.

Mordaunt, who came third in the leadership contest, said she backed Truss because of her “graft, her authenticity, her determination, her ambition for this country”.

Truss pushed her hard stance on post-Brexit Northern Ireland negotiations and her plans to immediately cut taxes as she made her pitch to Tory grassroots members, with the foreign secretary saying that the “business-as-usual” approach was not working.

“My vision is bold, it is different, but it is needed,” Truss said.

“And I believe people voted Conservative in 2019 because they wanted something new. They didn’t want more of the same.”

Mordaunt’s endorsement comes after defence secretary Ben Wallace and chancellor Nadhim Zahawi also backed the foreign secretary in the past few days.

Truss is a strong favourite with bookmakers, however a fresh poll tonight in The Times showed Sunak may be closing the gap.

The poll put him just six points behind Truss, after trailing by more than 20 in a survey last week.

Sunak went after Truss’ tax plans again at tonight’s hustings, saying the UK cannot rack up debt “which we just put on the country’s credit card, and then ask our children and grandchildren to pick up the tab”.

He also said he was the “change candidate” and took a jab at Truss for supporting Remain in the 2016 Brexit referendum.

He said Truss had been “a cabinet minister before I was an MP”.

Sunak said: “When it came to the Brexit referendum, when I was told that my career would be over before it begun, when we did have a bunch of doomster predictions – which I remember certain people were campaigning on – where was I on that divide?

“I supported change, I supported Brexit and I believed in my principles then and I believe in my principles now.”

In an attack on Sunak’s record at the Treasury, Truss said: “I do think the Treasury needs to change and it has been a block on progress. We haven’t changed [the Treasury infrastructure rules] since Brexit and I’m prepared to break away from the orthodoxy.”