President Donald Trump holds up a proclamation during a White House ceremony to establish tariffs on imports of steel and aluminum at the White House in Washington, March 8, 2018.

"Outside the agricultural areas, which will remain safely Republican in this cycle, the trade/tariff issue probably helps more than it hurts," said veteran Rep. Tom Cole of Oklahoma. "Somebody is finally doing something about China, which has simply ripped us off since we let them in the WTO. That is a net plus."

House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell , powerful advocates for the GOP's pro-business wing, have both warned against potential economic damage from Trump's course. But other Republicans, facing heavy losses in November's midterm elections, see the possibility of political benefit despite fallout on Wall Street and in farm states whose exports might suffer.

Here's something that might alarm financial markets as much as President Trump 's trade war threats: his reshaped Republican Party doesn't much mind them.

"From a Senate lens, it is helpful," added Josh Holmes, a top GOP Senate strategist, referring to Trump's "America First" combination of tariffs and an immigration crackdown. Tossing away prepared remarks on tax cuts, the president in West Virginia yesterday emphasized both issues as he took aim against vulnerable Democratic Sen. Joe Manchin.

As for investor fears that have sent markets tumbling, Holmes added: "Generally, the people freaking out are people with a lot of money. There aren't that many people with a lot of money."

That reflects the ongoing evolution of a Republican Party increasingly dependent on white working-class voters, while better-educated voters in growing, globally linked sectors of the economy drift toward Democrats. In last month's NBC News/Wall Street Journal Poll, twice as many Republicans as Democrats described trade with other nations as "a threat" rather than "an opportunity for economic growth."

Congressional Republicans still rely on wealthy business executives to finance their campaigns. They and Trump have delivered big benefits for their donor constituency through deregulation measures and the $1.5 trillion tax-cut whose proceeds will flow disproportionately to businesses and wealthy individuals.

Yet the tax-cut has yet not sheltered Republicans as much as they once hoped in the gathering 2018 campaign storm. The party holding the White House nearly always loses Congressional seats in mid-term elections, but Republicans fear results of recent special election foreshadow losses large enough to hand Democrats control of both chambers of Congress.

Last November, Republicans suffered a stunning Senate loss in Alabama. This week, a poll in Tennessee showed Democratic ex-Gov. Phil Bredesen leading GOP Rep. Marsha Blackburn for the Senate seat of retiring GOP incumbent Bob Corker.

Last month, Democrats captured a Pennsylvania House district that Trump won easily in 2016. So far, 38 House Republicans have declined to seek re-election in a year Democrats need to gain 23 seats to recapture their majority.

Dave Wasserman, a top analyst of House races at the Cook Political Report, draws a striking conclusion from the failure of ads touting tax-cuts to save the Republican seeking that Pittsburgh-area seat. Public support for the tax cuts is weak enough, he says, that attention on tariffs or even the president's relationship with porn star Stormy Daniels helps Trump's approval ratings, and his Republican allies, more.

Some strategists for the GOP, strongly identified with free trade since the Reagan era, disagree. Media consultant Kim Alfano called it "disastrous" to shift attention away from tax cuts toward trade conflict and potential damage to a strong economy.

"Tax cuts were a clear win," Alfano said. In addition to tangible benefits in higher worker paychecks, added pollster Kristen Soltis Anderson, "it proves that Washington is capable of getting something done."

Whether tariffs or any other issue can reshape election outcomes this fall is unclear. Fighting China over trade appeals to much of Trump's blue-collar constituency, but tariffs and their consequences would also hurt chunks of his base whose livelihoods depend on imported steel and exported farm products.

And in any event, survival of the GOP's majority requires reducing its current double-digit deficit among independents. Since that deficit stems largely from consistent concerns about Trump, even the most focused and aggressive Republican campaigns have limited ability to alter it.

"There are things we can control," Rep. Cole concluded. "We can't control the president."