Washington (CNN) President Donald Trump's recent moves on trade have turned an issue long considered part of the Republican orthodoxy into a political landmine for his own party.

Last week, Trump's administration announced steep tariffs on steel and aluminum from close allies Canada, Mexico and the European Union. In return, all three have promised retaliatory actions of their own. And on Friday, Trump that he "wouldn't mind" scrapping the North American Free Trade Agreement.

In Washington, the moves frustrated some GOP lawmakers. Perhaps none slammed Trump's decision more pointedly than retiring Sen. Bob Corker from Tennessee, who compared the President's moves to something that would happen in Venezuela.

"I am working with like-minded Republican senators on ways to push back on the president using authorities in ways never intended and that are damaging to our country and our allies. Will Democrats join us?" Corker tweeted.

And in several key races across the country, Republicans find themselves on the defensive over Trump's trade agenda.

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