FILE PHOTO: Anti-Brexit demonstrators waving EU and Union flags are reflected in a puddle in front of the Houses of Parliament in London, Britain, March 28, 2018. REUTERS/Toby Melville

LONDON (Reuters) - Britain’s upper house of parliament on Tuesday inflicted another defeat on Prime Minister Theresa May’s government, voting in favor of staying in the European Union’s single market.

The House of Lords voted 245 to 218 in favor of the amendment to the government’s key Brexit blueprint that will sever political, financial and legal ties with the EU.

The amendment is opposed by the government and can potentially be overturned in parliament’s lower chamber, where May has a slim majority.