Tony Blair, UK prime minister, suffered a blow to his plans on Monday to renew the Trident nuclear missile system when a member of his government quit ahead of a key parliamentary vote on the issue.

The resignation of Nigel Griffiths, deputy leader of the House of Commons, came as Mr Blair faces a substantial rebellion Wednesday by members of his Labour party in a parliamentary vote on Trident. While the prime minister is committed to renewing Trident, the issue is totemic for Labour, which was opposed to nuclear weapons in the 1970s, and a large number of its MPs remain hostile. Some are facing fierce anger in their constituencies.