Joe Biden has a major potential weakness that nobody is talking about: Latinos. He has been losing this constituency by big margins in the primaries so far, and his terrible record on immigration issues could easily depress Latino turnout in the general election. Worse, his campaign has shown no indication that it will even try to address the problem.

Nominating Biden runs a significant risk that he will fail to turn out this core Democratic constituency and lose to Trump.

Ever since Bernie Sanders' campaign ran aground in the South in 2016, his failure to attract more black support has been a major focus of media attention. Given his argument that only a multi-racial working class coalition can defeat Trump, it is a fair criticism. Indeed, Sanders spent much of the last few years trying to build more black support, though it apparently did not work that well.

However, the Latino-American vote has gotten much less attention, despite the fact that the national Latino population is about a third larger than the African-American one. Here Sanders has also been conducting an extensive outreach campaign, and by all accounts it is working very well. He won Latinos in Nevada by 36 points; in California by 35 points, and in Texas by 13 points.

Conversely, while Sanders has indeed failed to woo African-Americans so far, there is little question that he would get their votes in a general election. Favorability polls show that black voters have very positive views of Sanders, and reporting shows that they swung to Biden in South Carolina almost entirely because they were convinced that Biden was most likely to defeat Trump. African-Americans have an entirely understandable caution about Republican rule, and one can't exactly fault them for going with a perceived winner. But if Sanders were the nominee, he would certainly get a huge super-majority of black support.

Incidentally, Sanders' main error in his black outreach may have been not cultivating enough trusted surrogates in the black community. His campaign did not even ask for an endorsement from Rep. Jim Clyburn, who seems to have single-handedly saved Biden's campaign. While it's unlikely Sanders could have gotten that support, it was foolish not to try.

But on the other hand, Biden is scarcely even asking for Latino support. About the best he has done is quiet damage control after the July debate last year when he offended immigrant-rights groups by saying unauthorized immigrants need to "get in line" and that it was good policy to prioritize legal status for richer, high-skilled immigrants.

This is not so surprising, since Biden has chosen to barely campaign at all. His strategy from the start has been to limit campaign events, town halls, and media interviews, and coast to the nomination on name recognition and establishment support. Even Rachel Maddow has been reduced to begging for an interview on the air. This is obviously because Biden is suffering serious cognitive decline, and any public events pose the risk of yet another rambling word salad that will be passed around online.

Unlike Sanders (who has a very solid record on civil rights and racial justice issues) and black voters, Latinos have good reason to be suspicious of Biden. As a senator in the '90s, he supported several harsh war-on-crime bills that made it easier to detain and deport even legal immigrants. More importantly, Biden was vice president under Barack Obama, who pursued mass deportations with such fervor that immigrant rights activists dubbed him "deporter-in-chief." Obama's record is so horrible that liberals rightly outraged about Trump's immigrant abuse have on several occasions mistakenly identified pictures of children in cages that happened under Obama as something Trump had done. But Biden has refused to apologize for the deportation record, and only grudgingly admitted in mid-February that it was a "big mistake." Worse, when an immigrant rights activist asked Biden about the issue last November, Biden got angry and snapped, "You should vote for Trump." Immigrant rights group RAICES Action gave Biden's platform a C+ on immigration policy, while Sanders got a B+ (the highest of any candidate).

Of course, immigration policy is not the only thing Latinos care about. In a 2016 survey, they expressed similar concerns as the rest of the Democratic electorate, with education, the economy, and health care getting top billing. But 70 percent still said immigration is "very important," and 69 percent said the same about "how Hispanics are treated" — which in this country is generally a proxy for immigration policy.

There are significant Latino populations in the swing states of Arizona, Nevada, Florida, and Colorado — and since they make up nearly 40 percent of Texas, fully turning out that vote could very well win that state and the presidential election at a stroke. It is a terrible risk to put up a nominee who once again gives every indication of taking this constituency for granted.