WASHINGTON (Reuters) - Republican President Donald Trump’s market-jolting promise to slap heavy U.S. tariffs on steel and aluminum imports has earned him praise from an unusual quarter - Democratic lawmakers.

Some Democrats, mainly from Rust Belt states, but from other areas too, hailed the president’s plan for tariffs of 25 percent on steel and 10 percent on aluminum.

“This welcome action is long overdue for shuttered steel plants across Ohio and steelworkers who live in fear that their jobs will be the next victims of Chinese cheating,” said Senator Sherrod Brown, a liberal and populist Democrat from Ohio.

Senator Bob Casey, a Democrat from neighboring Pennsylvania, said in a statement that it had taken the administration too long to act, but that Trump’s announcement on Thursday was a “welcome step.”

That kind of language clashed with a generalized strong worry among most Republicans, long-time free trade champions, that Trump’s move could trigger an international trade war.

Paul Ryan, the Republican speaker of the U.S. House of Representatives, through a spokesman urged Trump to reconsider his plan and its potential unintended consequences.

Trade is an issue where Trump has consistently bucked mainstream Republican views, instead adopting throughout his campaign and as president a strongly populist stance in which he promised to defend American workers.

In his stunning November 2016 election victory over Democratic nominee Hillary Clinton, Trump carried rust-belt industrial states, such as Ohio, Pennsylvania, Michigan and Wisconsin, partly by appealing to blue-collar workers’ frustrations with Washington’s free-trade orthodoxy.

Last year Senate Democrats unveiled a trade proposal that emphasized protecting workers from foreign competition and tagged China as a “trade cheat” that threatens U.S. jobs - the sort of language Trump has used.

Oregon Democratic Senator Ron Wyden, who often criticizes Trump for one thing or another, issued a statement saying he was pleased Trump “recognizes the importance of addressing these challenges, and finally intends to take action.”

Democratic Representative Tim Ryan, whose northeastern Ohio district encompasses an area once known as “Steel Valley,” tweeted: “China has been eating our lunch for decades. These actions will protect good-paying jobs in Ohio and across the country.”

Trump said on Thursday he planned tariffs of 25 percent on imported steel and 10 percent on aluminum products, with a formal announcement to come next week.

Democratic Representative Bill Pascrell of New Jersey urged the president to move quickly. “Let’s get it done,” he said.

But not all Democrats agreed. “We need a thoughtful and aggressive response to China’s overproduction of steel and aluminum, but blanket tariffs are not the answer,” Colorado Senator Michael Bennet said in a statement, adding that Trump’s action “will invite retaliation and isolate us further from our trading partners.”