Possible Clues:

• It will kill the bill
• Block in Washington
• Live together, retaining right to say 'no'
• The power to prohibit or reject a proposal
• Presidential ''thumbs down''
• Prohibit some progressive tokenism
• Power to kill a bill
• Prevent legislation through rigging of vote
• Nix from the governor
• Forbid you to get one round to see your pet