There are two reasons I think Labour may struggle in this election. Firstly, the remaining fractures within the PLP that undermine a lot of the good policy work done, and secondly the media portrayal of Corbyn that has been embedded since he came to become leader. From my experience, many people are not politically engaged enough to study manifestos of parties due to both interest and time, and will look to the news, be that in the form of print media or broadcast media to give them an indication of what’s going on. The (not entirely incorrect) media narrative of Corbyn being a poor leader immediately turns people off the idea of him becoming PM, and the (in my view, incorrect) rhetoric that he would be a danger to the country further deepens this stance.
Surely, though, you must accept that Blair to Corbyn is much more than merely a change of leader - it’s a complete change of dynamic and party stance. You won’t find many defending Blair’s decision to privatise portions of the NHS through PFI schemes and thinking that things like that are traditional Labour stances is wrong. They even re-branded as ‘New Labour’ so as to demonstrate a divide from the public perception of the party throughout the 70s and 80s.