A national union of postal workers denounced Republican nominee Donald Trump as dangerous for inciting racial tensions Monday when endorsing Democratic nominee Hillary Clinton.

The American Postal Workers Union (APWU) is the largest union of mailmen in the country at 200,000 members. The APWU National Executive Board made its endorsement for Clinton roughly a week after she was officially nominated at her party convention. Union leadership took the opportunity to attack her rival, Trump.

“Trump’s blatant attempts to incite racial, ethnic, and religious divisions are offensive and dangerous,” APWU Secretary-Treasurer Liz Powell declared in a statement. “We need unity and solidarity.”

Trump has gained popularity by positioning himself as a tough guy who isn’t afraid to speak his mind. His brash tone and his stance on immigration have also earned him many critics. Trump wants tougher border security and has called for a temporary ban on Muslims entering the country from regions known for terrorism.

The APWU also notes the hotel mogul would be bad for workers because of his stance on policies like the minimum wage. Trump has changed his views on the minimum wage a few times throughout the campaign but eventually settled on the position it should be a state rights issue, PolitiFact detailed.

Nevertheless Trump has said he is fighting for workers and wants to use trade policies to keep jobs from going overseas. He has opposed the Trans-Pacific Partnership out of concern the massive trade deal will lead to increased outsourcing. Many national unions hold a similar position on the trade deal.

The APWU is not the first union to oppose Trump and his bid for the White House. The AFL-CIO has also claimed he is a racist and bigot. It is now leading a coalition of unions to defeat him on the state level by promoting grassroots opposition.

Trump has also faced opposition from Las Vegas service unions which want to represent workers at one of his hotels. The Culinary Workers Union Local 226 and the Bartenders Union Local 165 won a vote Dec. 7 but hotel management has yet to recognize it despite federal pressure.

Hotel management has fought the unionization campaign and challenged the vote on the grounds the unions misled workers.

The Trump campaign did not respond to a request for comment by InsideSources.