A casino owned by billionaire Carl Icahn withdrew an offer to restore health insurance for its striking workers Monday after the union refused to put the measure up for a vote 18 days into a walkout. The Trump Taj Mahal had given striking Local 54 of Unite Here until Monday to vote on its offer.  About 1,000 union members from the Taj Mahal's food and beverage and housekeeping departments went on strike July 1 after the union was unable to agree on a contract that restored health care and pension benefits that a bankruptcy judge terminated in 2014.  Dealers and security are not included in the walkout, and the Taj Mahal remains open.