Teamsters President Sean O’Brien is navigating an internal revolt over the union’s decision not to endorse Vice President Kamala Harris, with local chapters rushing to endorse her anyway. The Teamsters executive board voted to stay neutral in the presidential race on Wednesday,

For the first time in nearly three decades, the International Brotherhood of Teamsters won’t endorse a candidate in the presidential race — a blow to the Democratic Party, which has reliably received the union’s approval for years.

The Teamsters president, Sean O’Brien, has shown an openness to former President Donald J. Trump, dividing the powerful union. Neither candidate will be the beneficiary of its considerable organizing muscle.