The Maastricht Treaty , which greatly increased the powers of the European Commission , was widely unpopular according to opinion polls .
All three of the main parties had pledged to support Maastricht Treaty 's ratification in the House of Commons .
The Maastricht Treaty , which greatly increased the powers of the European Commission , was widely unpopular according to opinion polls , but all three of the main parties had pledged to support its ratification in the House of Commons .