When Trump shames Toyota, here’s what he’s really trying to do

Donald Trump speaks at the USA Thank You Tour event at the Wisconsin State Fair Exposition Center in West Allis, Wisconsin, U.S., December 13, 2016.
Shannon Stapleton | Reuters
Donald Trump speaks at the USA Thank You Tour event at the Wisconsin State Fair Exposition Center in West Allis, Wisconsin, U.S., December 13, 2016.

We've all heard the old saying: "If you can't beat 'em, join 'em." But in politics, the more clever move can be summed up by saying: "If you can't beat 'em, steal their best supporters." Donald Trump is continuing to do just that to the Democrats, and the supporters he's stealing are the unions.

Trump's attack tweets against different companies may seem pretty random, but look closer. When he calls out Carrier, Ford, GM, Lockheed-Martin, Boeing, etc., all of the companies he's targeting have something in common: They're either unionized companies or in generally unionized industries. He did it again Thursday with this swipe at Toyota:

Trump's protectionist threats continue to anger many conservative economic purists. But Democrats are the ones who should be irate, and they will be once they figure out what Trump is doing and doing successfully. He's pulling their most important source of financial and ballot box support right out from under them.

His protectionist and border security message, which became evident right from the first day he announced his campaign, clearly spoke to union rank-and-file members across the country. While too many of the so-called experts were focusing on what they saw as offensive comments about illegal Mexican immigrants, union voters must have been listening with an open mind. The numbers prove it, as Trump did better among union voters than any Republican presidential candidate since Ronald Reagan.

This makes a lot of sense politically. After the Iraq War went south and the financial crisis hit in 2008, the Republican brand died nationally. The GOP was still a viable party in statewide elections, especially in its stronghold regions in the reddest of red states.

Trump seems to be the only Republican candidate who realized, and still realizes, that espousing traditional GOP messages won't work on the national stage anymore. That meant grabbing some of the traditional Democratic core supporters to make up the difference. And doing so meant sounding less like a Republican and more like a protectionist, pro-union Democrat.

And it's not just about total voter numbers. As Hillary Clinton found out the hard way, eroding union support for Democrats leaves any Democratic presidential candidate vulnerable in the supposedly "blue wall" states like Michigan, Wisconsin, and Pennsylvania that are all rich in Electoral College votes.

And then there's the money. And we're talking big money. The list of the top financial election year donors to the Democratic Party reads like a list of unions in the phone book. Almost all of them donate almost exclusively to the Democrats and they also provide crucial ground support on Election Day to get out the vote. It is almost impossible to overstate their importance to the Democrats' chances of wining any election at any level.

Indeed, Republicans have used this union-stealing strategy before. In addition to Reagan badly damaging his challengers' chances by almost winning the union vote in 1980 and 1984, Richard Nixon actually won a majority of them in 1972. Those presidential elections were all landslide wins for the Republicans.

The good news for the Democrats is that in each of those elections and the 2016 contest, the individual winning GOP presidential candidate didn't have strong enough coattails to create , or in Trump's case, increase, Republican majorities in Congress. But for Democrats and liberals who have made Trump their singular enemy, perhaps that's no consolation. And if any current or future GOP candidates for key Congressional seats take up Trump's pro-union tune, the losses could be devastating for the Left.

It's not that Trump has only gone after companies or industries with union workers. On the campaign trail and in some other venues he bashed hedge funds, Wall Street, and promised to do something about rising drug prices. But his most intense and enduring focus remains on the auto industry and manufacturers that either have, or once had, a lot of unionized employees.

Nixon didn't get much of a chance to cater to unions, and Reagan did it infrequently with his protectionist policies to rescue Harley-Davidson and the steel industry. Trump looks like he's going to make this a regular priority. How the Democrats will respond to him and this strategy is their problem.

Expect this to continue throughout his presidency. And all it takes is a look at the election map to see why. Trump's siphoning of union support from the Democrats brought him a narrow election victory, it's only logical that he'll do what it takes to siphon yet more to ensure more support and a bigger re-election margin in the coming years.

Commentary by Jake Novak, CNBC.com senior columnist. Follow him on Twitter @jakejakeny.

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