The U.K. House of Lords approved an amendment to the government's Brexit legislation that would give Parliament a "meaningful vote" on any deal, delivering a blow to Prime Minister Theresa May who now faces a showdown with pro-EU lawmakers in the lower house.

Members of the upper house voted 354-235 in favor of the Brexit bill amendment that would empower Parliament to shape what the government should do next in case it fails to reach a pact with the EU, or if such a deal is rejected by lawmakers, Reuters reported.

The amendment compels ministers to report to Parliament by Jan. 21, 2019, regarding the prospect of securing a deal with the EU, according to The Guardian. The government will then have two weeks to return to the lower House of Commons to present its next plans, which will be subjected to a vote by lawmakers.

The lower house will take up the Brexit bill amendment June 20. Pro-EU members seeking a compromise on the issue have warned they could bring down the government if their demands are not met, Reuters noted.