UK Labour Party leader Jeremy Corbyn says the challenge to his leadership has created a “massive opportunity” to unite people across the country.

Addressing up to 10,000 of his supporters at a campaign event in Liverpool on Monday, Corbyn said the ongoing battle for leadership in the party provides an opportunity to unite Britons against the “Tory philosophy.”

“I don’t see this leadership contest as a distraction,” said Corbyn. “I see it as a massive opportunity to reach out to people all across this country and have the strength and confidence [to stand up to] those who tell us that nothing we’re trying to do is possible, that what we have to do is compromise with the Tory philosophy and free market ideas and all will be well.”

Corbyn, who needs to beat former BBC producer Owen Smith in order to keep his throne as the opposition leader, described the audience as the largest crowd he had at a leadership campaign rally.

“This is a campaign about, on one level, the leadership of the Labour Party, but it’s also a campaign about how we do politics in our society,” he noted, before getting more specific about issues such as mental health services, workers’ rights and homelessness.

Corbyn’s bid for re-election received another boost on Monday, when the Communication Workers Union (CWU) formally endorsed him, marking his third union endorsement after ASLEF and UCATT.

He welcomed the endorsement and pledged to reach out beyond the party boundaries, rejecting opposition claims that he exists in a “remote bubble of adulation.”

“If you’re going to be effective in politics you’ve got to listen to people, some of whom may not agree with you, some of whom may have criticisms, some of whom may have constructive suggestions for you. The idea that I live in some kind of remote bubble of adulation is nonsense,” he explained.

Corbyn’s opponents challenged his leadership for what they call inadequate efforts to keep the UK in the European Union (EU).

He has until September 21 to appeal to voters and defeat Smith. The results will be announced in a Liverpool conference three days later.