Dan O’Sullivan is a career left-of-center labor organizer. He currently works as the director of communications for the Service Employees International Union (SEIU), one of the largest and most influential labor unions in the United States with deep ties to the Democratic Party establishment. Previously, he worked as a spokesman for the union. O’Sullivan has been involved with SEIU public relations for more than twenty years.  
In addition to his long-time affiliation with the SEIU, O’Sullivan sits on the advisory committee of Our Story, a communications and messaging consulting service for left-of-center politicians and activist organizations.  Our Story touts its efforts to insert left-progressive narratives into the discourse of American society, and teaches its clients to push their rhetoric “over and over again” because “repetition is the key to persuasion” and can “build new neural pathways” in listeners’ minds. 
Service Employees International Union Career
Dan O’Sullivan has been the director of communications for the SEIU since April 2019, but started out as a spokesman more than two decades prior.   Throughout his tenure, he has been involved in attempting to mitigate the fallout from several controversial incidents involving the union.
2001 Disputed SEIU Local Election
In February 2001, while working as an SEIU spokesman in Washington, DC, O’Sullivan issued a statement that the union would be intervening in a local dispute over alleged rule violations in a Pennsylvania SEIU local chapter. The new chapter president was accused of taking outside financial assistance, a violation of the union constitution, as well as failing to attend chapter meetings and pay dues, making him ineligible for the position. O’Sullivan announced that the SEIU would conduct a hearing to review the allegations. 
2017 Lawsuit Against SEIU
In September 2017, a member of a local SEIU chapter sued the national organization, alleging an extensive track record of illegal activity. O’Sullivan, who at the time was still a spokesman for the union, declined to respond to media inquiries about the allegations, which included but were not limited to fraud, racketeering, embezzlement, bribery, and coercion, according to court filings. 
2019 SEIU Internal Dispute
In March 2019, the SEIU’s staff union – the organization representing the union’s own employees – voted to go on strike because they refused to accept the contract which the SEIU management had offered them. The union’s management indicated in its negotiation documents that it would not make any further concessions, stated that the union “will be well prepared to conduct the business of our members without interruption in the event of a strike.” However, as reported by the Huffington Post, O’Sullivan stated in his capacity as spokesperson that management welcomed the staff union’s strike authorization vote, and called it a show of the same labor organizing principles that the SEIU claims to champion. At the same time, O’Sullivan called the offer from SEIU management “excellent.” 
Our Story Hub
Dan O’Sullivan is a member of the advisory board of the Our Story Hub, itself a project of the Proteus Fund, which facilitates donor-advised grants and acts as a “pass-through” organization for funds directed to left-of-center causes. O’Sullivan sits on the board along with numerous representatives of other left-of-center organizations. These include other labor unions, such as the AFL-CIO and the American Federation of State, County, and Municipal Employees, as well as think tanks such as the Center for American Progress and the Economic Policy Institute.