Automation is one of the big sleeper issues of the 2020 presidential campaign. Most candidates aren't focusing on it by name, even though it profoundly shapes key themes in the race: the U.S. economy, jobs and friction between the haves and have-nots.

Why it matters: "If we stay on the trajectory we're on currently, we're going to have greater income inequality, less social mobility, greater political unrest and greater income insecurity," says Elisabeth Reynolds, executive director of the MIT Task Force on the Work of the Future.

Unchecked, job losses from automation could knock out bottom rungs of traditional career paths, worsen inequality and increase political polarization.

Fast advances in AI and robotics threaten to fundamentally alter both low- and high-skilled jobs, increasing the urgency for political leaders to address the issue, Reynolds says.

The big picture: The effects of automation fit into a puzzle that includes trade policy. But while trade and China hog political attention, automation gets passed over, leaving a gaping hole in critical preparations for the future of work.

Where it stands: The 2020 field is split on automation, and not just along party lines.

There's a lack of "original thinking" on the issue from the candidates, says MIT economist Daron Acemoglu.

The debate gets muddy because automation is tied up with other massive forces threatening the economy, including trade. Plus, it's hard to disentangle the potential upsides from the pain, or put hard numbers on either.

But Warren's hard-line trade-only argument is "too extreme," says Reynolds. "I think we know that it's both automation and trade."

"There are high levels of uncertainties here and that only makes it a more queasy issue," says Brookings' Mark Muro. "Some will benefit; some won’t. Parts of jobs could go away, but other new parts emerge."

Voters, too, may be underestimating the importance of automation. Instead, their views are largely a litmus test for their politics.

When Gallup and Northeastern University asked Americans to rate the seriousness of various threats to jobs earlier this year, 56% of Republicans said immigration is a major threat, compared to just 5% of Democrats.

By contrast, 60% of Democrats said increased trade barriers are a major threat, versus 17% of Republicans.

AI, which underlies automation, was less important for both parties: 35% of Democrats and 34% of Republicans said AI was a major threat.

The bottom line: For the gravity of the changes it's bringing, automation deserves more emphasis than it's getting.

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