(CNN) When President Donald Trump heads to western Pennsylvania on Saturday, he'll be trying to save a struggling Republican congressional candidate locked in a tough special election race.

He'll also be trying to save himself and his party from an embarrassing defeat in a district he won by 20 points in 2016 and one filled with the white, blue-collar voters who led him to victory.

The White House scrambled to vet the order Trump signed Thursday after he made it known that he wanted to approve the tariffs before his campaign stop on Saturday, where he is set to hold a rally for Republican state Rep. Rick Saccone.

The President's moves on tariffs this week were, in part, designed to gin up support for Saccone; Trump has told associates that he hopes the tariffs will play well with his base, including voters in Pennsylvania 18th District around Pittsburgh and in the heart of America's steel industry.

But the tariffs, some Republicans said, may not be the silver bullet Trump is hoping for.

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