Former Republican Senate leader Mitch McConnell pulled no punches Thursday in criticizing Donald Trump’s tariffs, saying the president’s economic policy is “the last thing we need.”

“As I have always warned, tariffs are bad policy, and trade wars with our partners hurt working people most,” tweeted McConnell, an Alabama native who continues to represent Kentucky in the Senate but did not run for another term as Republican leader.

“Tariffs drive up the cost of goods and services. They are a tax on everyday working Americans. Preserving the long-term prosperity of American industry and workers requires working with our allies, not against them. With so much at stake globally, the last thing we need is to pick fights with the very friends with whom we should be working with to protect against China’s predatory and unfair trade practices,” McConnell tweeted.

“Tariffs make it more expensive to do business in America, driving up costs for producers and consumers across the board,” the senator continued.

Trump is placing steep new tariffs on virtually all U.S. trading partners, stoking fears of rising prices for consumers and deepening trade wars.

The tariffs hit allies and rivals alike. The Republican president is placing a 10% baseline tax on trading partners around the globe and is setting heftier levies on major partners with which the U.S. has a trade deficit like China, the European Union and Japan.

While Trump had suggested the tariffs were a negotiating tool to lower the taxes paid on U.S. exports, he described his plan as one that would boost domestic manufacturing and raise federal revenues. It has unsettled global financial markets and sparked concerns about inflation and slowing global growth.

Trump has not responded to McConnell’s tweet as of Thursday afternoon.

Despite being members of the same political party, Trump and McConnell have had a long-running personal feud.

Trump has lobbed racist attacks at McConnell’s wife, former Trump Transportation Secretary Elaine Chao. The president also accused McConnell of not being “mentally equipped” to lead Republicans in the Senate.

McConnell said the tariffs will have devastating economic consequences for his state.

“Make no mistake: goods made in America will be more expensive to manufacture and, ultimately, for consumers to purchase, with higher broad-based tariffs,” McConnell said. “At a time when Americans are tightening their belts, we would do well to avoid policies that heap on the pain. We ought to strengthen our friendships abroad, and reinforce our allies as pillars of American prosperity and security.”

The Associated Press contributed reporting.