Support for Rival Soft Brexit Plan Builds in U.K. Parliament

The proposal, which includes a bolted-on customs union arrangement, is building up steam after the main opposition Labour Party and the Scottish National Party backed it.Prime Minister Theresa May has set herself against staying in the EU’s single market and a customs union, because to do so would wreck two key aims of the pro-Brexit campaign: to end unlimited immigration from the EU and to set the U.K. free of EU tariffs to strike trade deals around the world.The House of Commons is debat