Jo Swinson is “optimistic and very hopeful” of growing the Liberal Democrat parliamentary party, as she spoke of “huge frustration” among “many MPs” with their own parties over Brexit.

The Liberal Democrat deputy leader, one of two contenders for the party leadership, accused Labour of “letting down the country with their equivocation on Brexit”, adding that Jeremy Corbyn “has been sitting on the fence for so long he will have splinters”.

It follows Labour deputy leader Tom Watson’s fresh call this week for Labour to campaign for a second Brexit referendum, plus former Change UK MP Chuka Umunna’s decision to join the Lib Dems.

Ms Swinson, who is bidding to become her party’s first female leader in a contest against former energy secretary Sir Ed Davey, also turned her fire on Tory frontrunner Boris Johnson claiming he was “scared” to talk.

Speaking to the Press Association, she argued it was “absolutely possible” to stop Brexit and said the Lib Dems were the “best, strongest and most consistent rallying point for Remain”.

Ms Swinson said: “We clearly will be the place that is best placed to win in large parts of the country. Am I also open to working with other parties? I mean I will do anything that I can to stop Brexit.”

In Peterborough she said discussions were held to put forward a single People’s Vote candidate, adding: “I think the fact that we were prepared to do that was important, I think many people in the country want to see cooperation and joint working.”

Liberal Democrats Autumn Conference 2018
Liberal Democrat deputy leader Jo Swinson (Gareth Fuller/PA)

She said: “I hear there is huge frustration that many MPs have with their own parties at the moment, particularly on this issue of Brexit, but it goes beyond that as well, the way in which the Labour and Conservative parties in particular are being taken off to the extremes and my door is always open to have those conversations … I would say I’m optimistic and very hopeful that we will be growing our Liberal Democrat parliamentary party.”

On Mr Johnson, Ms Swinson said: “This is a man who can hardly open his mouth without gratuitously offending a particular group of people and revels in it.

“I think there’s so many reasons why he’s not fit to be prime minister and just the fact that he seems like he’s taking this for granted and that he doesn’t need to subject himself to the scrutiny that his fellow candidates are going though, it just highlights the huge privilege that he seems to think he deserves.”

Ms Swinson also noted the country was “crying out” for a liberal movement to take on the forces of nationalism and populism “the likes of (Nigel) Farage and (Boris) Johnson”.

She said: “I believe I’m the best person to build that movement. In order to do that we need to reach out, we need to reach out to new voters across the country, across the generations and across traditional party lines.”

MPs who wanted to “avoid the catastrophe of no deal or a very hard Brexit” had “got some very serious thinking to do and they need to get on board and back a People’s Vote”, she said, adding: “I think the weeks in the autumn in the run up to October 31 will be crucial.”