Jeff Flake appeared on NBC's "Meet The Press" Sunday and said that President Trump should be challenged in the 2020 primary election.
"If implemented these tariffs will do just what tariffs have always done".
"As a Republican who believes in free trade, limited government, economic freedom, I couldn't be re-elected in my party right now", said Flake, he won his Senate seat in 2012 after serving six terms in the U.S. House.
Trump's tariffs, which he announced last Thursday, were met with swift opposition from numerous president's fellow Republicans who say they will harm the economy.More news: Barbershop study trimmed black men's hair and blood pressure (copy)
"We are extremely anxious about the consequences of a trade war and are urging the White House to not advance with this plan", House Speaker Paul D. Ryan spokeswoman AshLee Strong said last week.
Flake, whom many speculate has his own presidential ambitions, did not indicate whether he meant to be that challenger.
He went on to say that it would be a tough go for any Republican to run a primary campaign against Trump.
On the tariffs, Flake said Trump had introduced "dual poisons" for the economy, by erecting new trade barriers and then introducing uncertainty by suggesting he might make some exceptions for certain countries.More news: Probation for student who rubbed tampon blood on Jamaican's bag
Flake, one of the GOP's most outspoken Trump critics, is stoking speculation about his 2020 plans with a Friday appearance in New Hampshire as part of the "Politics & Eggs" speaker series, which draws presidential hopefuls to the first-in-the-nation primary state.
The orders were signed over the objections of more than 100 congressional Republicans, who urged Trump in a letter to at least pare back the scope of the tariffs.
But Flake says "that's not to say it will stay that way".More news: Sevilla boss Vincenzo Montella reveals Champions League tactics