(CNN) - President Donald Trump's pitch on trade at the G7 in Canada will be no doubt a tough sell, especially since many prominent lawmakers -- from the President's own party -- are criticizing the idea of imposing tariffs on steel and aluminum imports.
"We've stopped the regulatory burden, we've made America's tax system more competitive, that produced certainty and great optimism in the economy, which is one of the reasons we've had these economic results," said Sen. Ron Johnson, a Wisconsin Republican. "Let's face it, we're now on the opening shots of a trading war, (creating) greater uncertainty and puts all that at risk."
A cadre of Republicans went to the White House on Wednesday to meet with the President on trade ahead of the G7 summit. Many of them were concerned that taking a tough line on trade could ultimately back fire.
"We have the best economy we've had in decades and decades," said Sen. James Lankford, a Republican from Oklahoma. "I'd like to be able to keep that going, I don't want to have something be able to interrupt that."
A lot of the worry from congressional Republicans is about the instability the tariff policy could lead to.
"The concern has been that this is more or less an unguided missile because a retaliation could occur in other sectors that really hurt the United States economy," said Sen. John Cornyn, a Texan and the second most powerful Republican in the Senate.
The tariff move is also a surprise coming from a Republican President -- the leader of a party which traditionally encourages free trade.
"Republican orthodoxy has been to shun tariffs and have free trade, so this is really -- there's nothing conservative about this policy, nothing," said Arizona Republican Sen. Jeff Flake, who is retiring at the end of his term.
Republicans in Congress are also worried the White House approach to trade is unfairly hammering friendly countries like France, Germany and Canada. Meanwhile China, a country the President talked tough about during the campaign, is the beneficiary of a major trade deal -- the decision to settle with telecommunications giant ZTE despite direct calls from Republican leaders to the contrary.
"China has been stealing as much intellectual property as it can and otherwise trying to compromise America's lead when it comes to innovation and technology of our national security technology in particular," Cornyn said.
But despite their worries, Republicans are hoping that these moves by the President are part of a bigger plan to strike a grand bargain in Canada. Some, like Sen. Lindsay Graham, a South Carolina Republican, just want to know what those plans are.
"I think all of us want to know what a better deal looks like, what's the end game with the White House, what's your plan, how do we get there?" Graham said. "I don't want to undercut his position, but I would like to know how this movie ends."
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