Consumers may be opening up their wallets wide right now, but a long-time Wall Street researcher warns strong spending is on borrowed time.

DataTrek Research co-founder Nicholas Colas predicts it's on the verge of dangerously weakening due to tariff risks — a situation that could ultimately push stocks much lower.

"That trade war issue ... really is top of mind for me," he said this week on CNBC's "Trading Nation."

Colas cites low unemployment as the main reason why Americans have felt so good about spending money. The latest monthly reading put the unemployment rate at 3.8 percent.

"So far, employers [and] companies have not really thought about the effect of trade wars in context of capital budgeting, capital planning, hiring," Colas said.

Colas believes President Donald Trump's tariff threats have already harmed corporate America by leaving companies no choice but to re-assess their business plans whether a trade war happens or not.

He expects companies to begin scaling back hiring and capital-expense spending in coming months to address uncertainty. Once that happens, he said, the employment rate will inevitably tick up and consumers will tighten their purse strings out of fear.

"That’s the beginning of the economy rolling over, and with that stocks," Colas said.