European officials are preparing to make a fresh push to salvage a nuclear deal with Iran , offering to send a top European Union negotiator to Tehran in an effort to break a stalemate in talks, according to Western diplomats. Enrique Mora, the European Union coordinator of the negotiations, has told Iranian counterparts he is ready to return to Tehran to open a pathway through the deadlock, the people said. So far, Iran hasn’t responded with an invitation, the people added.