He has previously estimated that a 20% across-the-board tariff plus 60% duties on Chinese goods would cost that family $3,900.

On Monday he said a 100% tariff on Mexico would bring the tab up to $5,700.

While many in the business community have dismissed Trump's tariff promises as bluster, Trump's record stretching back to 2016 has shown he tends to keep — or at least try to keep — his tariff promises.

Many expect he will impose some flavor of historic new duties if he wins, but the key question appears to be if the courts intervene to block it.

Other last minute promises on semiconductors and health care

Another last-minute policy debate is over the 2022 Chips and Science Act, which was signed by Biden and is in the process of sending about $50 billion to the semiconductor sector. That has spurred more than $400 billion in new investments by chip makers.

Late last month Trump told podcaster Joe Rogan "that chips deal is so bad," prompting Vice President Kamala to remind swing states — specifically Michigan and Arizona — that much of the money was headed to them.

But the issue got a new level of attention last Friday when House Speaker Mike Johnson responded to a question about whether he would try to repeal the law, which he voted against, by saying "I expect that we probably will."

It didn't help that the comment came during a stop in upstate New York, where money in that bill is set to help spur thousands of jobs.

An array of lawmakers immediately weighed in to defend the law and Speaker Johnson immediately backtracked and claimed to have misheard the question. He said he is only looking to reform the law.

As for the chance of repeal actually happening. Rhodium Group director Reva Goujon counseled caution in a Yahoo Finance appearance Monday, She said "The CHIPS Act is extremely unlikely to be repealed. There is bipartisan support for industrial policy, especially for chips.”

But Trump's last pre-election word on this issue appears to be that podcast appearance, where he told Rogan "when I see us paying a lot of money to have people build chips, that's not the way" — suggesting that tariffs were a better approach.

Johnson has also had to clarify remarks in recent days on what he and Trump would do on healthcare after Trump has floated repealing the law while declining to offer a plan for what would replace it.

Johnson again amplified the issue when video emerged of him with supporters saying "no Obamacare" and adding the program needed massive reform to work.

It was yet another comment that Johnson has sought to clarify; it was also seized upon by Democrats and could be a factor for voters in the final days of the 2024 contest.

Ben Werschkul is Washington correspondent for Yahoo Finance.

Every Friday, Yahoo Finance's Rachelle Akuffo, Rick Newman, and Ben Werschkul bring you a unique look at how US policy and government affect your bottom line on Capitol Gains. Watch or listen to Capitol Gains on Apple Podcasts, Spotify, or wherever you find your favorite podcasts.

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