You’d think none of that would be all that controversial. Disabilities strike across age groups, racial barriers, and partisan lines. In this election, even this is a polarized issue—though the roots of that split actually date back to before Donald Trump was a major political figure.

Disability politics used to be bipartisan. The Americans with Disabilities Act was primarily authored by Senator Tom Harkin, an Iowa Democrat. It passed the Senate and House overwhelmingly—91-6 and 377–28, respectively, and was signed into law by President George H.W. Bush in 1990. When he signed the law, Bush said:

Now I sign legislation which takes a sledgehammer to another wall, one which has for too many generations separated Americans with disabilities from the freedom they could glimpse, but not grasp. Once again, we rejoice as this barrier falls for claiming together we will not accept, we will not excuse, we will not tolerate discrimination in America…. To those Members of the House of Representatives with us here today, Democrats and Republicans as well, I salute you. And on your behalf, as well as the behalf of this entire country, I now lift my pen to sign this Americans with Disabilities Act and say: Let the shameful wall of exclusion finally come tumbling down.

Eighteen years later, Bush’s son George W. Bush signed some expansions of the ADA into law.

Since then, however, things have sputtered. In 2012, the Senate failed to ratify a United Nations treaty called the Convention on the Rights of Persons With Disabilities. Democrats supported the treaty, but Republicans were split. On the pro side were George H.W. Bush and Bob Dole, the former Senate GOP leader and presidential candidate who was injured during World War II. On the con side were a bloc who warned on extremely dubious grounds that the treaty would allow the UN to meddle in U.S. courts. In the end, the treaty failed, despite Dole himself appearing on the Senate floor to lobby. It needed two-thirds of votes to pass, but was only able to garner 61.

The Trump campaign has only exacerbated any such splits. The most egregious moment came when he mocked New York Times reporter Serge Kovaleski. Trump falsely claimed he’d seen Muslims celebrating 9/11 in the streets in New Jersey, and pointed to reporting Kovaleski, who was then a reporter for The Washington Post. When Kovaleski, who has a congenital condition affecting his joints, contradicted Trump, Trump mocked him, doing a physical impression of Kovaleski:

Trump denied that he was mocking Kovaleski, despite the evidence. He also argued that his legally required compliance with the ADA proved his support for the disabled, although as Gideon Resnick pointed out, Trump has been sued repeatedly for violating the ADA. He also appeared to mock conservative pundit Charles Krauthammer, who is paralyzed from the waist down, saying, “I get called by a guy that can't buy a pair of pants, I get called names? Gimme a break.”