WASHINGTON, May 31 (Xinhua) -- U.S. Treasury Secretary Steven Mnuchin and U.S. Trade Representative Robert Lighthizer opposed President Donald Trump's plan to impose additional tariffs on Mexican goods, U.S. media reported Friday.

The surprise decision, which was not supported by the two senior officials, was spearheaded by the president's senior adviser Stephen Miller, known for his hardline immigration stance, the CNBC reported, citing a source close to the White House.

Trump said on Thursday he would impose a 5-percent tariff on all imported Mexican goods beginning June 10 so as to pressure the country to halt undocumented migrants crossing the border, and will gradually increase tariffs until the problem is remedied, a move that worries many.

Lighthizer argued that the announced tariffs on Mexico could jeopardize the ratification of the U.S.-Mexico-Canada Agreement (USMCA), a proposed replacement for the North American Free Trade Agreement (NAFTA) that is already facing a bumpy road in the Democrat-controlled House, The Wall Street Journal (WSJ) cited people familiar with the situation as saying.

"Lighthizer is not happy," an administration official told the WSJ.

"Imposing tariffs on goods from Mexico is exactly the wrong move. These tariffs will be paid by American families and businesses without doing a thing to solve the very real problems at the border," said Neil Bradley, executive vice president and chief policy officer of the U.S. Chamber of Commerce.

"Instead, Congress and the president need to work together to address the serious problems at the border," Bradley said in a statement Thursday following the president's announcement.

Republican senator Chuck Grassley, chairman of the Senate Finance Committee, also blasted the president's decision. "Trade policy and border security are separate issues. This is a misuse of presidential tariff authority and counter to congressional intent," Grassley said.

"Following through on this threat would seriously jeopardize passage of USMCA, a central campaign pledge of President Trump's and what could be a big victory for the country," he said.

Earlier on Thursday, the White House sent a draft of "Statement of Administrative Action" to Congress, clearing the way for the administration to submit an enforcement bill to Congress after 30 days, which in turn starts a 90-day clock for an up-or-down vote on the trade deal.

If the tariff comes to pass, Mexico "should respond in a forceful way," said Jesus Seade, the trade negotiator for Mexican President Andres Manuel Lopez Obrador, on Thursday.

Despite wide-ranging objections, President Trump continued to defend his plan. "Mexico makes a fortune from the U.S., have for decades, they can easily fix this problem. Time for them to finally do what must be done!" the president said in a tweet Friday.

"The Tariff is about stopping drugs as well as illegals!" he said in another tweet.