The College Democrats of New Jersey were preparing to make an endorsement in one of the country’s most closely watched U.S. Senate primaries when calls began to come in from someone in touch with the campaign of Tammy Murphy, the presumptive front-runner and the wife of the state’s governor. The caller, a female college student who works as a youth coordinator for the Democratic State Committee, wanted to know what Murphy’s campaign could do to block the group from endorsing Murphy’s main rival,