The chairman of the UIP was Evan Falchuk, a former health care executive who submitted enough signatures to be on the 2014 gubernatorial ballot.

Prior to the 2016 presidential primaries, Massachusetts Secretary of the Commonwealth William F. Galvin stated that officials had noted an "inexplicable increase" in new members of the United Independent Party, especially amongst casual voters who were registering for the first time or online (UIP membership grew from 1,867 in February 2015 to roughly 21,000 by the end the year).

Galvin became concerned that many of these voters had accidentally enrolled in the party in the belief that they were registering as "unenrolled", commonly referred to as independent, and would be allowed to vote in either primary.

In late January 2016, Galvin sent a letter to the 20,914 enrolled members of the party, informing them that they may have signed up incorrectly.

Falchuk did take issue with Galvin's statement to WGBH radio, in which he remarked that voters had likely enrolled with the UIP by accident.

Falchuk stated that he felt that this was "an elected official using his office not to educate voters ... but rather to say, 'We don't think you should be involved in that party.'"