There are plenty of prominent Republicans who have telegraphed their displeasure with Donald Trump's candidacy. Some Republican members of Congress have even refused to endorse Trump. But until today, no Republican member of Congress had crossed party lines and endorsed Hillary Clinton.

Now Rep. Richard Hanna (R-NY) has done just that. In an op-ed for the Syracuse Post-Standard, Hanna offered a scathing evaluation of Trump’s fitness for the White House and vowed to vote for his Democratic opponent.

"I found him profoundly offensive and narcissistic but as much as anything, a world-class panderer, anything but a leader," Hanna wrote, describing him as "deeply flawed in endless ways."

Trump, Hanna argued, is "a self-involved man who is worth billions yet is comfortable — almost gleefully — using bankruptcy laws to avoid the consequences of his own choices. A man of character would not defend his actions but rather display shame and or at least regret. He is unrepentant in all things. Think about those average people who paid for his choices."

In an interview about his endorsement, Hanna said that the last straw was Trump’s quarrel with Khizr and Ghazala Khan, the parents of a fallen Muslim American soldier. "I was stunned by the callousness of his comments," Hanna said.

Hanna has long been one of the most liberal members of the House Republican caucus. And he’s retiring in January, which means he’s not reliant on Republican volunteers and infrastructure to win reelection. So we shouldn’t necessarily expect a lot of other Republicans in Congress to follow Hanna’s lead.

Still, having a prominent Republican openly denounce Trump isn’t going to help him win in November.