"Corporations eagerly hire cheap, exploitable migrant labor to break strikes, weaken unions, and force employees of all nationalities and backgrounds to accept lower wages and worse working conditions. This abuse is why, until relatively recently, many folks on the left railed against illegal immigration.
Legendary labor activist Cesar Chavez famously condemned it. Former President Obama, probably the most talented politician in living memory, noted, "The idea that we can just have open borders is something that ... as a practical matter, is unsustainable."
Sen. Bernie Sanders, in 2015, emphasized the need for limits on immigration. He decried open borders as a "Koch brothers proposal," referring to the billionaire libertarians who believe almost nothing should restrict businesses. Open Borders would "make a lot of Americans poorer" and lead to a glut of desperate people who'd "work for $2 or $3 an hour."
Multiple peer-reviewed studies have confirmed the validity of their concerns, and proven that a massive expansion of the labor pool drives down wages, especially for minority workers.
So it's no wonder that ordinary voters, including those on the left, support measures to ensure that jobs only go to Americans and legal immigrants. For instance, 58% of Democrats want to "mandate that all employers use the federal electronic E-Verify system to help ensure that they hire only legal workers for U.S. jobs," according to a Rasmussen poll taken in late March."