The prime minister says that because he has criticised the performance of devolution does not mean he opposes it.
SNP Westminster Leader Ian Blackford has criticised the prime minister's position on devolution.
Labour leader Sir Keir Starmer said devolution was "one of the proudest achievements" of the last Labour government.
By Kate Whannel
Coffee cups and single-use plastic can help explain why this proposed law is proving controversial.
By Alun Jones
BBC Wales Political Unit
Mayor of Greater Manchester Andy Burnham has said more devolution would help the UK.
By Ione Wells