oppose — to act against or provide resistance to; combat.
refuse — to decline to accept (something offered): to refuse an award.
renounce — to give up or put aside voluntarily: to renounce worldly pleasures.
veto — the power or right vested in one branch of a government to cancel or postpone the decisions, enactments, etc., of another branch, especially the right of a president, governor, or other chief executive to reject bills passed by the legislature.
halt — to falter, as in speech, reasoning, etc.; be hesitant; stumble.
protest — an expression or declaration of objection, disapproval, or dissent, often in opposition to something a person is powerless to prevent or avoid: a protest against increased taxation.
repel — to drive or force back (an assailant, invader, etc.).
disendorse — (transitive) To cease to endorse; to withdraw endorsement.