Jeremy Corbyn has said wealthy elites are trying to "hijack" Brexit as he formally launched Labour's campaign.
Speaking in Manchester, the Labour leader promised a reckoning for "tax cheats, rip-off bosses and greedy bankers" if Labour wins the election.
But in a BBC interview, he declined to say categorically whether he would take Britain out of the EU if elected.
Asked by Laura Kuenssberg if he would go through with Brexit if there was a bad deal on the table, he wouldn't say.
The Labour leader earlier told activists that the question of whether the UK would leave the EU had been "settled" and the task now was to act in the national interest and not show "who can be toughest with Brussels".
Although the election was not about Brexit in itself, he said there was a clear difference between his approach and that of the Conservatives, who he said were prioritising narrow party interests.
In what the Conservatives dismissed as an "angry and divisive" speech, Mr Corbyn told activists that his mission was to transform Britain, saying "we have four weeks to take our wealth back and four weeks to show what kind of country we are".
Repeating his argument that the economy was "rigged" against ordinary people, he said a Labour government would take action against asset strippers, tax evaders and those who "ripped off workers and consumers".
"We have four weeks to ruin their party," he said.
Speaking afterwards to the BBC's political editor Laura Kuenssberg, he said that he was angry at levels of poverty and inequality in the country, which he believed were shared by the public.
"They are very angry. They see the growth of the super-rich and very wealthy corporations and they see their communities left behind. Their anger is palpable and I think we have to address that."
Mr Corbyn, who campaigned to remain in last year's referendum but subsequently voted to trigger the Brexit process, said the outcome of the 2016 vote was clear and the next government's job was to get a "good deal" on withdrawal.
But pressed on several occasions whether, as prime minister, he would allow Brexit irrespective of the kind of deal achieved, he declined to say.
"I don't know any more than you what is going to happen in the future but I do know that we are not approaching this from megaphone diplomacy.
By Laura Kuenssberg, political editor
Jeremy Corbyn says "Brexit is settled".
His team is adamant that if he is in Number 10, we would leave the European Union.
It's possible, in theory, that if the deal on the table didn't look too pretty they would want to keep going back to the negotiating table somehow until the offer improved.
Labour is also committed to giving Parliament a final vote on what's on offer.
But, in the big picture, today the Labour leader tried to draw a line under the issue after not a little bit of Labour agony over it in the last few months.
"We are not approaching this from threats... our view is you have to talk to them, negotiate with them and recognise there is quite a lot of common interest."
If elected, he said his negotiating priorities would be guaranteeing tariff-free access to EU markets, ensuring the rights of EU nationals living in the UK and maintaining employment rights such as the working time directive.
"People know there's been a referendum and a decision was made a year ago," he said.
"We have set out very clear terms for negotiations... we are negotiating a trade agreement with Europe and protection of the things we have gained from the EU."
In the run-up to Tuesday's speech, Mr Corbyn insisted he would stay on as Labour leader even if the party loses at the general election. He told BuzzFeed: "I was elected leader of this party and I'll stay leader of this party."
Although facing a challenge to win on 8 June, Mr Corbyn told supporters he was determined to show "things don't have to remain the way they are".
He promised decent homes for all, extra funding for schools and vowed to "draw a line" under privatisation in the health service, social care, energy market and the rail network.
Prime Minister Theresa May has attempted to portray the general election as being about Brexit, urging voters to strengthen her negotiating hand in talks set to begin next month.
Conservative chairman Patrick McLoughlin said Mr Corbyn was "too weak to stand up to the leaders of 27 EU countries".
"This angry, divisive and chaotic speech makes clear the choice at this election - strong and stable leadership with Theresa May, or uncosted, nonsensical policies from Jeremy Corbyn," he said.
"He didn't mention the deficit or controlling immigration - because he'd wreck our economy with higher taxes and more debt."
Lib Dem leader Tim Farron, who has promised a second referendum on any Brexit deal, said suggestions the UK's future in Europe was settled was "further proof" of Labour's "inability to stand up to the Tories on the most important issue facing our country".
The SNP said Labour's performance in council elections last week showed any talk of them forming the next government was "utter fantasy".