There's also the matter of a massive 80 seat majority, which any Opposition leader is always going to struggle with. 

Polls as we have seen are fickle.

If Starmer can cut the Conservative majority to under 50 in the next election it would be deemed a success IMO. How he's going to win back that red wall who defected to Tories is always going to be his biggest challenge.

If anything is going to bring down Bojo it's himself and his own party. Hence why he was so keen to appease his backbenchers and delaying the lockdown.