Despite earlier comments during the leadership campaign that there might be circumstances in which he would favour withdrawal,[256] in September 2015, Corbyn said that Labour would campaign for Britain to stay in the EU regardless of the result of Cameron's negotiations, and instead "pledge to reverse any changes" if Cameron reduced the rights of workers or citizens.[257] He also believed that Britain should play a crucial role in Europe by making demands about working arrangements across the continent, the levels of corporation taxation and in forming an agreement on environmental regulation.[258]