The Greens are in chaos after the party’s manifesto launch was overshadowed by a series of stumbling interviews by leader Natalie Bennett including one she herself admitted was “excruciating”.

Reaction to the series of media appearances, organised to promote the Greens general election programme, was heated, with many comparing the series of interviews to a “car crash,” while others suggested she had given the “worst interview ever”.

<noframe>Twitter: Nick Ferrari - If you missed one of the worst interviews ever by a political leader tune in after 9 <a href="http://www.twitter.com/LBC" target="_blank">@LBC</a> for a reprise <a href="https://twitter.com/search?src=hash&q=%23greenparty" target="_blank">#greenparty</a></noframe>

She repeatedly failed to answer questions about the party’s economic policy, stumbling when asked for basic details about the Green platform.

Following a particularly bungling appearance, with LBC Radio, when she went silent for long periods, Miss Bennett admitted to suffering from “mind blank,” and confessed her “excruciating” performance had been impaired by a “huge cold” after she struggled to explain the party’s housing policy.

In one exchange with presenter Nick Ferrari, she was asked several times how much the Green policy of removing tax relief on mortgage interest for private landlords would bring in, responding: "Erm ... well ... that's part of the whole costing."

<noframe>Twitter: Tim Stanley - Incredibly Awkward Interview With Natalie Bennett | LBC <a href="http://t.co/0NnFc5WQWz" target="_blank">http://t.co/0NnFc5WQWz</a> via <a href="http://www.twitter.com/lbc" target="_blank">@lbc</a></noframe>

Pressed on the cost of building 500,000 social homes, which the party has promised, she went on: "Right, well, that's, erm ... you've got a total cost ... erm ... that we're ... that will be spelt out in our manifesto."

Mr Ferrari responded: "So you don't know?" To which Miss Bennett said: "No. Well ... er."

At one point, Miss Bennett, who is standing as a candidate in Holborn and St Pancras, sought to explain her below-par responses, saying: "As you can probably hear I've got a huge cold."

Mr Ferrari said: "I'm terribly sorry to hear that ... You don't actually know what this is going to cost, do you? Do you think you might perhaps have genned up on this a little bit more Natalie Bennett?"

He went on to describe the interview on Twitter as one of the worst ever by a politician.

<noframe>Twitter: Owen Jones - Unbearably awful interview. Green supporters will be exasperated that a great political opportunity has been trashed. <a href="http://t.co/ha0hqXRez0" target="_blank">http://t.co/ha0hqXRez0</a></noframe>

In an earlier interview, with the BBC’s Radio 4 Today Programme, Miss Bennett also appeared unclear about the details of her party's economic programme.

She added that Britain should deal with the threat from Russian planes approaching UK airspace by offering “concessions” to President Vladimir Putin.

During a press conference to launch the manifesto, Miss Bennett was asked if her weak performance had overshadowed the event.

Baroness Jones, the chair, tried to stop her responding before Miss Bennett insisted on answering, saying: "It was absolutely excruciating in the studio. All I can say is occasionally one just has a mind blank, that happens.

"I've been presenting the Green Party's policies up and down the country. I've been delighted to do that. I'm delighted with the response they get and I'm delighted to have the backing of all 54,000 Green Party members."

Miss Bennett later told the BBC's Daily Politics Show she was "sorry" for letting down Green Party members by failing to represent the party's policies properly in the LBC interview.

Natalie Bennett v Nick Ferrari: the worst ever interview by a politician?

Here is part of the interview between Miss Bennett and Mr Ferrari:

The radio presenter challenges the Green Leader over her claim that social housing would be funded by removing tax relief from private landlords. Asked several times how much it would bring it:

NB: "Erm ... well ... that's part of the whole costing."

NF asks for the cost of expanding social housing.

NB "Right, well, that's, erm ... you've got a total cost ... erm ... that we're ... that will be spelt out in our manifesto."

NF: "So you don't know?"

NB: "No. Well ... er."

After some time NB says the total cost would be £2.7 billion.

NF "Five hundred thousand homes, £2.7 billion - what are they made of, plywood?"

Long pause.

"Um ... At a cost of £60k per home ... What we are talking about, what we want to see is the possibility of homes being built."

NF Suggesting £60,000 would not pay for "much more than a large conservatory," adds: "How are you going to pay for the land?"

Pause followed by coughing.

NF: "Are you all right?"

NB: "Yeah. As you can probably hear I've got a huge cold."

NF: "I'm terribly sorry to hear that ... You don't actually know what this is going to cost, do you?"

NB says the party had a "fully costed programme" that would be published before the election before coming up with the figure of £6 billion without saying what it related to. "We're also looking at investing ... (silence) ... we've got the fully costed figures here."

NF: "You've said that on several occasions."

Coughing.

NB: "Basically we're talking about an overall saving of £4.5 billion."

NF: "Do you think you might perhaps have genned up on this a little bit more Natalie Bennett?"

Coughing

NB: "We're talking about a whole range of ... what we're talking about is a whole range of issues ranging from the economy, from the NHS, homes, climate."

NF: "Yes, I've only time for two unfortunately. I wish we had more time."