ORLANDO, Fla. >> Tens of thousands of Teamsters members earlier this month rejected a five-year contract agreement with United Parcel Service, unhappy with a proposal to create a new class of drivers with lower pay.

But after less than half of the eligible union members cast ballots, one of the largest collective bargaining contracts in the nation has been ratified.

Fifty-four percent of the ballots were “no” votes, but under a Teamster rule, a rejection requires two-thirds of the voters to vote down the contract when less than half of eligible members participate.

Now, many Teamsters members are angry, divided and feel like their union leaders have betrayed them.

“This destroys unions,” said Sean Mason, a UPS driver in the Orlando, Florida area. “They had 54 percent of the people vote no and they ignored the vote.”

Atlanta-based UPS has one of the nation’s largest unionized workforces, with the Teamsters representing around 240,000 UPS drivers, package sorters, loaders and clerks. UPS workers represent the largest share of members of the International Brotherhood of Teamsters, whose president, James Hoffa, is the son of the legendary Teamsters president Jimmy Hoffa, whose 1975 disappearance is an enduring mystery.

During the Oct. 5 UPS vote, 44 percent of eligible Teamsters members cast ballots for the national contract. Under a rule in the Teamster’s constitution, in cases where less than half of eligible members vote, at least two-thirds of voters must oppose the contract for it to be rejected.

Another contract for about 12,000 UPS freight workers also was rejected earlier this month, but two-thirds of eligible members cast ballots.

In a message to members on the Teamsters website for UPS workers, union leaders said their hands were tied.

“And as we saw in the 2016 U.S. Presidential election, winning the popular vote does not necessarily win the election when the Constitution requires you to win the Electoral College vote,” the message said. “As Teamsters, we too must abide by the rules in our Constitution.”

The contract won’t be implemented until side agreements with regional and local Teamster groups are done being negotiated.

Teamsters spokeswoman Kara Deniz said Teamsters negotiators have asked UPS to return to the bargaining table to continue talks on the national contract.

“Nonetheless, less than 50 percent of the eligible members voted and the union’s Constitution quite clearly specifies what happens in that situation. There is no basis for confusion,” Deniz said in an email.

UPS said in a statement after the vote, “UPS is operating on a business-as-usual basis and customers should continue to trust UPS for reliable, high-quality service.”

Steve Gaut, a UPS vice president for public relations, said Wednesday the company wouldn’t comment further on the contract vote since side agreements and the contract for freight workers are still being negotiated.

Sean O’Brien, who is running to replace Hoffa in 2021, said any acceptance of the contract by union leaders should be halted.

“This is bad not only for the Teamsters but the entire labor movement,” said O’Brien, a Teamsters international vice president from Boston. “It’s the largest collective bargaining contract in the country and you’re sending a message to other unions.”