(Mark Blinch/Reuters)
People participate in a labor activists' march in Lansing, Michigan, June 1, 2009. For decades, unionized manufacturing jobs have been considered the surest path to middle-class prosperity and realizing the vaunted American dream for blue-collar workers.

Protectionism has grown quite popular as American workers continue to worry about losing jobs to other countries.

And politicians have zeroed in on these anxieties as they vie for the top job in the White House.

Donald Trump made the debate over free trade one of the central topics of his campaign after criticizing China, Mexico, and Japan. He even once suggested putting a 45% tariff on Chinese imports.

Meanwhile, Hillary Clinton has recently edged away from the Trans Pacific Partnership (TPP) after previously calling it the "gold standard" of trade agreements.

Bank of America Merrill Lynch's global economist Ethan S. Harris and US economist Lisa C. Berlin argue that this shift has two major near-term implications.

"First, we now believe the Trans-Pacific Partnership is less likely to pass the US Congress," the duo wrote in a note to clients. "Given the recent very negative rhetoric from both sides of the aisle, we now think passage of TPP is a very close call under a Clinton Presidency and is unlikely under Trump."

And "a second implication is that conflicts over currencies could escalate," they continued.

As they explain in greater depth regarding point two:

The US Treasury has been flirting with naming China and other countries 'currency manipulators' for many years. Recently, they put a big spotlight on China, Japan, Korea, Taiwan and Germany. They said that each had exceeded two of three thresholds for being designated for 'bilateral engagement' — (1) a bilateral trade surplus with the US of over $20 billion, (2) an overall current account surplus of 3% of GDP, and (3) persistent purchases of foreign currency that amount to more than 2% of GDP over a year. Under a Clinton administration, we would expect Treasury to follow through on these rules, while they would likely be tightened further under a Trump administration.

Although the aforementioned short-term implications are certainly interesting to consider, perhaps the more interesting thing about this whole populist shift is the huge gap between economists' opinions on free trade and those of regular Americans.

Mainstream economists pretty much all agree that free trade is "good" for an economy in the long-run (even though within an economy there will be some people who benefit less), while trade-restrictive measures hurt consumers.