UK General Election- What chance to win has Labour, promising to renegotiate EU deal and hold a second referendum on it?

None!.....They've said they'd try to negotiate a new deal but also that they would vote AGAINST it.

They have no idea what they are doing.

Labour committed in their 2017 election manifesto to a deal that explicitly protects workers' and consumers' legal rights and the environment and as much as possible retains the benefits of the Customs Union and Single Market. Voters' liking for this soft Brexit and rejection of the Tories' hard Brexit was one reason why Theresa May ended up having to bribe the DUP for a majority in parliament.

The revisions Labour agreed to May's deal went some way towards satisfying its election commitments but Johnson's deal delivers none of those things. Labour's plan is to offer voters in a referendum the choice between remain and a deal consistent with its 2017 commitments. I should have thought that would be popular with the majority of voters who either want to remain in the EU or want the UK to retain a relationship with the EU that doesn't leave the country reliant on a trade deal with the US that would involve US healthcare companies taking over parts of the NHS and the NHS pay higher prices for drugs manufactured by US companies among other downsides.

They change their tune as often as  the weather changes. What can they re-negotiate, that has not been thrashed out in the past 3 years? If they had any realistic proposals, why have they not promoted them? Corbyn's negativity on everything is predictable.

I think it's going to be a hung parliament again, we need politicians who can unify rather divide unlike the lot we have now. That will mean that no one gets all they want.