The American Postal Workers Union (APWU) endorsed Sen. Bernie Sanders (I-VT) for the Democratic Party’s 2020 nomination for president on Thursday.

The financially troubled United States Postal Service (USPS) has an estimated 500,000 full-time employees, almost all of whom are members of a union. There are seven different unions that represent USPS employees.

The two largest unions are the AFL-CIO-affiliated National Association of Letter Carriers (NALC), which has 270,000 members (including both current and retired USPS employees), and the APWU, also AFL-CIO-affiliated, which represents 200,000 current and retired USPS employees. “APWU members belong to the Clerk, Maintenance, Motor Vehicle Service (MVS), or Support Services divisions,” according to the union’s website.

In June 2016, the NALC endorsed Hillary Clinton, one month before the Democratic National Convention. It has not yet endorsed a candidate for president in the 2020 campaign.

“The U.S. Postal Service lost more than $2 billion during the second quarter of the fiscal year, putting it on track to finish the current year more than $7 billion in the red—way worse than the nearly $4 billion in losses it posted last year,” Reason.com reported in May.

“The U.S. Postal Service lost $8.8 billion in fiscal 2019, more than doubling its losses from the previous year,” Government Executive reported in November.

The APWU endorsement of Sanders was not unexpected as the 200,000-member union endorsed him for president in 2016, but the timing, coming just days before Monday’s Iowa caucuses, added to the perception that momentum is growing for the Sanders campaign.

The APWU announced its endorsement of Sanders in this statement, released Thursday:

The American Postal Workers Union announced today that its National Executive Board has voted to endorse Bernie Sanders for president. “We’re pleased that a number of presidential candidates have taken positions and actions supportive of postal workers and expanding union rights. But when we judge candidates by their long-term and consistent actions, Bernie Sanders stands out as a true champion of postal workers and all workers throughout the country,” said APWU President Mark Dimondstein. In their deliberations, APWU’s board members cited Sanders’ record on postal issues including his speaking out against USPS policies that have degraded mail service; his fierce opposition to proposals that would sell off all or part of USPS to private interests; his efforts to keep post offices and mail facilities open; and his support for enhanced customer services such as postal banking. “As the lone senator blocking postal privatizers from appointment to the Postal Board of Governors it was clear that Bernie Sanders is on the side of postal workers.” said Dimondstein. APWU’s leaders also cited Sanders’ sustained commitment to improving the lives of all working people. In their discussions, APWU National Executive Board members mentioned the Vermont senator’s long record of walking picket lines, fighting for living wages and universal health care, as well as his advocacy for improved veterans’ benefits and the expansion of Social Security. “Senator Sanders was a champion of workers’ rights long before he became a candidate for president,” said APWU Secretary-Treasurer Liz Powell. “Like the APWU, he is a firm believer in social and economic justice for all. It’s no wonder that he is ranked as the most popular member of the U.S. Senate.”

According to the Real Clear Politics Average of Polls as of Saturday, Sanders leads among likely attendees of the Iowa Democratic caucuses with 23 percent support, followed by former Vice President Joe Biden at 20 percent, Pete Buttigieg at 16 percent, Sen. Elizabeth Warren (D-MA) at 15 percent, and Sen. Amy Klobuchar (D-MN) at ten percent. The political blog 538.com reported on Friday that Klobuchar may be experiencing a final-days surge.

Sanders and Warren “have long called for expanding the services offered by post offices, especially in rural communities, to include things like banking,” ABC News reported this week:

National labor unions wield a great deal of influence in the Democratic primary, though many have yet to pick sides in the still-crowded 2020 field. The National Nurses United backed Sanders in November after endorsing him in 2016. Biden’s campaign got a boost last year with the endorsement of the International Association of Fire Fighters. … In its statement endorsing Sanders on Thursday, the postal workers union said that the Trump administration “has released a series of proposals that would end the universal service requirement and also would make significant changes in the pricing structure of mail products.” It also noted that there have been calls to sell the federally run postal service to private corporations. “When we defeat Donald Trump, we’re not going to privatize and cut the Postal Service. We’re going to expand and strengthen the Postal Service,” Sanders tweeted in reaction to the endorsement. The union promised to “encourage its members and their families who live and work in all 50 states” to join Sanders rallies and volunteer for campaign activities. It also said it would launch voter registration drives and urge its members, their families and their friends to choose “vote by mail” options in states without restrictions on absentee balloting.

Though several other candidates, Warren in particular, are viewed positively by APWU members. One candidate, in particular, Pete Buttigieg, has active opposition within the union. That opposition stems from his work, while employed by the consulting firm McKinsey on a project for the United States Postal Service (USPS). The recommendations from that project that were implemented by the USPS were widely unpopular among APWU members, and Buttigieg’s efforts to distance himself from the project have not been well received on the campaign trail.

APWU has 2,600 members in Iowa who live and work in every community and zip code in the state. The union has communicated the Sanders endorsement to every member in the state.