One of the most telling moments of last night’s Republican presidential debate was when Marco Rubio accused Donald Trump of hiring foreign workers rather than Americans for his resorts. Rubio exploited a long-time liberal critique of modern Republicanism: that while the party proclaims family values, the GOP’s betrothal to free market capitalism undermines the American family.

Here is Rubio’s assault:

“My mom was a maid in a hotel. And instead of hiring an American like her, you’ve brought over 1,000 people from all over the world to fill in those jobs instead.”

Rubio was intending to attack Trump while emphasizing his own American Dream story of a hard working immigrant family raising itself up, a contrast to Trump’s silver spoon upbringing. Rubio did much more than that, however.

That exchange made the front page of the New York Times today, running alongside another story titled “Foreign Labor Fills Vacancies at Trump Club,” which details how a Trump resort bypasses Americans to hire short term foreign workers. According to the story, the foreigners are all but indentured servants. Their low wages suppress the wages available to American workers, when the Americans can find jobs at all.

What is happening here is the story of a traditionally economically royalist party having to deal with the populist awakenings of its socially conservative/populist base. Yes, lower income conservatives are angry at the Republican establishment, and a good deal of that anger is aimed at immigrants. But it has seeped into a realization that policies devoted to cutting taxes on the rich has produced little of value for the American worker. When a hard-working laborer like Marco Rubio’s mother isn’t hired, the economic distress cascades throughout the family.

Wealthy business interests in the Republican Party have long favored loose immigration laws for the very reasons Rubio has highlighted. Masters of the universe profit from cheap labor.  So long as the debate is about fences and who’ll pay for them, the inherent tension within the Republican Party remains dormant. But it can’t be contained.

This tension is not new though. Recall the Republican primary season of 2012, when Newt Gingrich and others attacked the “vulture capitalism” of Mitt Romney. To Romney and his one percent base, this was an unconscionable and un-American assault on success itself and a blasphemy upon its altar, unrestrained free market capitalism.

But for workers like those laid off at Bain Capital’s factories, and for hotel maids like Marco Rubio’s mother, the Romney and Trump brand of capitalism is a threat to their livelihoods, and to their families.