Throughout the conflict, the United Kingdom's government remained the strongest supporter of the U.S. plan to invade Iraq albeit originally seeking a UN Mandate. Prime Minister Tony Blair frequently expressed support for the United States in this matter, while Members of Parliament (MPs) were divided. Blair experienced a significant rebellion from many Labour MPs and in a debate in the House of Commons, he achieved a parliamentary majority with the support of most Conservative MPs and Ulster Unionists. Although the Conservatives were supportive of the Government's stance as a whole, a significant minority of their MPs rebelled against the party line, including figures such as Kenneth Clarke. The Liberal Democrats opposed the war, and their MPs were visibly unanimous on the issue. One former cabinet minister delivered a stinging personal attack on the Prime Minister, calling his behaviour 'reckless'. Robin Cook MP and a few other government ministers resigned to the backbenches over the issue. Clare Short MP threatened to resign from the cabinet, but then remained for two months before finally resigning on May 12, 2003. Cook, a former Foreign Secretary and at the time Leader of the House of Commons, delivered a resignation speech, which was received with a standing ovation. Cook indicated that while he agreed with most of Blair's policies, he could not support the war.