I just did it with the transcript of the Democrats's South Carolina Debate, and there's practically nothing on the subject. Warren mentioned immigration as one of the things she doesn't like about the institution of the filibuster.
Klobuchar said at the end of one speech "Final thing is comprehensive immigration reform. I have passed..." and then the moderator called "Time."
Finally, Sanders mentioned it when he was saying he wasn't "radical." Sanders has a list of things he's saying isn't radical (they are, of course) and he mentioned "immigration reform," which on Democrat stage only means Amnesty, as something that he defied Mayor Pete to say was radical. Aside from that, crickets.
The thing is, they're all agreed on opening the floodgates.
Sanders has said that his first executive act will be to reverse everything Trump has done to protect America, and to do so, he's willing to actually resume terrorist immigration:
My first executive orders will be to reverse every single thing President Trump has done to demonize and harm immigrants, including his racist and disgusting Muslim ban.— Bernie Sanders (@BernieSanders) January 27, 2020
Biden wants to increase immigration to two million a year:
ALERT: Joe Biden wants to almost triple immigration!— Team Trump (Text TRUMP to 88022) (@TeamTrump) August 9, 2019
2 million more EACH YEAR would:
🔻Crush wages for working class
🔻Kill blue collar jobs
🔻Ravage Medicare & Social Security
🔻Drain federal treasury
🔺Crowd schools & hospitals@realDonaldTrump puts American citizens first! pic.twitter.com/K90hUjEf83
And Bloomberg, in spite of being part sane in some ways, has always been crazily pro-immigrant, one of the "Billionaires For Open Borders."
"A couple of years later, @Mike2020 was touting the benefits of a low-wage workforce thanks to immigration. 'You and I both play golf,' Bloomberg pointed out to radio host John Gambling. 'Who takes care of the greens and the fairways in your golf course?'" https://t.co/TLZlGzlRzB— Andrew Good (@Drewbueno) February 14, 2020
So here's the problem for the Democrats—when they face Trump in the general election, they'll have no idea what to say about immigration in response to his attacks on them, because they'll never have heard any of it before.