Who is the culprit of painting it as a partisan issue.
This was unnecessary to say just enforce it the law. Why put a piblic stance on it. It's already implied they aren't welcome and the law will be enforced.
Pretty much every immigration law has been most strongly pushed by the most openly racist members of government in order to drive pro-white political sentiment. That has included both parties to some degree, at different times some more than others. But there's been a new growth in that direction in the last 20 years.I'm saying who did it first? When did it start?
Back in the early 2000s I used to hate-listen to a lot of conservative LA radio on some "know your enemy" shyt and one of the stations called KFI was pretty much an entirely anti-immigration lineup. The two worst were "Savage Nation", a national show by Michael Savage, and "John and Ken", a local California show. Both shows were COMPLETELY focused on racist anti-immigrant rhetoric with occasional anti-Black rhetoric sprinkled in here and there. There'd been anti-immigration activists operating for decades (like John Tanton's complex of White Nationalist orgs), but no one in the mainstream had ever promoted it like that as the #1 issue. Even ultra-conservatives like Rush Limbaugh only pushed immigration as one of many topics. I mean imagine, Ronald Reagan was the guy who had amnestied millions of illegal immigrants and he was a conservative hero. It wasn't on their radar like that before, their bigger red meat issues were taxes, abortion, guns, and crime.
The real turning point came in 2007-2013. George W. Bush was closer to the old school and more pro-immigration than the growing extremist wing. He tried to pass immigration reform in 2007, which eventually lost out due to inability of liberals and conservatives on either side of him to compromise. Anti-immigrant conservative voices kept attacking the issue heavy and Donald Trump stepped into political debates with racist rhetoric. But democrats and republicans tried to work something out every year and got to the point where the "Gang of Eight" compromise in 2013 passed the Senate by a substantial 68-32 margin, with all the Democrat votes and nearly 1/3 of the Republicans. But Jeff Sessions and his hardcore racist anti-immigrant communications director Stephen Miller were so upset by it that they sent an entire handbook to the House showcasing all the reasons they should never, ever pass immigration reform. And it worked, the bill was never brought up in the House, and immigration reform died. Donald Trump ran for president with race/immigration as his #1 issue and won on the issue. And that's where we are today.