The Connecticut chapter of a national teachers union has endorsed former Waterbury star teacher Jahana Hayes for Congress, according to a news release.

American Federation of Teachers Connecticut endorsed Hayes, a Democrat, to replace U.S. Rep. Elizabeth Esty in Connecticut’s 5th Congressional District.

Hayes, the 2016 National Teacher of the Year, is running in the Aug. 14 primary against former longtime Simsbury First Selectman Mary Glassman, who won the Democratic endorsement at the party’s convention in May.

Esty, a three-term Democrat, dropped her re-election bid after revealing she covered up an office abuse scandal involving her former chief of staff.

The 5th District, which stretches from the Danbury area to the Massachusetts border and the Farmington Valley, New Britain and Middlefield, is the most competitive Congressional seat in Connecticut.

The AFT Connecticut endorsement was Hayes’ second in as many days. On Monday, Hayes was endorsed by the Connecticut Working Families Party.

Hayes, a first-time candidate who was encouraged to run by U.S. Sen. Chris Murphy, D-Conn., has received several high-profile endorsements, including one in mid-June from U.S. Sen. Kamala Harris, D-Calif., who has been mentioned as a potential 2020 Democratic presidential candidate.

Glassman and Hayes will face off at their first debate on Sunday in Washington.