United Auto Workers reformers prevail in vote to choose president by direct election.

Members of the United Automobile Workers union have voted decisively to change the way they choose their president and other top leaders, opting to select them through a direct vote rather than a vote of delegates to a convention, as the union has done for decades.

The votes on the election reform proposal were cast in a referendum open to the union’s roughly one million current workers and retirees and due by Monday morning. Nearly 64 percent of the roughly 140,000 members who cast valid ballots favored a direct-election approach, according to a court-appointed independent monitor of the union.

“It is time to move forward on behalf of the over one million members and retirees of the U.A.W. in solidarity,” the union said in a statement.

The referendum was required by a consent decree approved this year between the union and the Justice Department, which had spent years prosecuting a series of corruption scandals involving the embezzlement of union funds by top officials and illegal payoffs to union officials from the company then known as Fiat Chrysler.

More than 15 people were convicted as a result of the investigations, including two recent U.A.W. presidents.

Reformers within the U.A.W. have long backed the one member, one vote approach, arguing that it would lead to greater accountability, reducing corruption and forcing leaders to negotiate stronger contracts. A group called Unite All Workers for Democracy helped organize fellow members to support the change in the referendum.

“The membership of our great union has made clear that they want to change the direction of the U.A.W. and return to our glory days of fighting for our members,” said Chris Budnick, a U.A.W. member at a Ford Motor plant in Louisville, Ky., who serves as recording secretary for the reform group, in a statement Wednesday evening. “I am so proud of the U.A.W. membership and their willingness to step up and vote for change.”

David Witwer, an expert on union corruption at Pennsylvania State University at Harrisburg, said the experience of the International Brotherhood of Teamsters, which shifted from voting through convention delegates to direct election in 1991, after an anti-racketeering lawsuit by federal prosecutors, supported the reformers’ claims.

Dr. Witwer said the delegate system allowed seemingly corrupt union leaders to stay in power because of the leverage they had over convention delegates, who were typically local union officials whom top leaders could reward or punish.

“Shifting the national union election process from convention delegates to membership direct voting was pivotal in changing the Teamsters,” he said by email.

At the U.A.W., leadership positions have been dominated for decades by members of the so-called Administration Caucus, a kind of political party within the union whose power the delegate system enabled.

Some longtime U.A.W. officials credit the caucus with helping to elevate women and Black people to leadership positions earlier than the union’s membership would have directly elected them.

But the caucus could be deeply insular. The Justice Department contended in court filings that Gary Jones, a former U.A.W. president who was sentenced to prison this year for embezzling union funds, used some of the money to “curry favor” with his predecessor, Dennis Williams, while serving on the union’s board.

Union officials have said Mr. Williams, who was recently sentenced to prison as well, later backed Mr. Jones to succeed him, helping to ensure Mr. Jones’s ascent.