President Donald Trump’s pick to serve as the next U.S. trade representative, Jamieson Greer, appeared before the Senate Finance Committee on Thursday and defended proposed tariffs from the Trump administration. 

Greer told lawmakers that the U.S. government previously raked in major funding from tariff revenues until the early 1900s, a time ‘when America truly was exploding as an international industrial powerhouse and we had a relatively high tariff rate.’

‘At the same time, we saw countries like the United Kingdom lowering their tariff rates and actually falling out of industrial competitiveness,’ Greer said to lawmakers. 

Greer also called for bolstering the U.S. manufacturing base, claiming that trade policy has major ramifications on economic and national security issues. 

‘If the United States does not have a robust manufacturing base and innovation economy, it will have little in the way of hard power to deter conflict and protect Americans,’ Greer said. ‘Trade policy can play an important role in ensuring that we have the economic security that leads to strong national security. I am convinced that we have a relatively short window of time to restructure the international trade system to better serve U.S. interests.’ 

Greer, who previously served as the chief of staff to the trade representative during Trump’s first term, played a key role in implementing tariffs during Trump’s first administration, the president said when unveiling Greer’s nomination. 

Specifically, Trump said Greer assisted with imposing tariffs on China and other nations and replacing the trade agreement with Canada and Mexico. 

A lawyer and Air Force Judge Advocate General’s Corps veteran with one deployment to Iraq, Greer’s role as U.S. trade representative would require him to negotiate with foreign governments on trade deals and disputes and membership of international trade bodies like the World Trade Organization. 

Greer’s confirmation hearing comes just after Trump announced he would impose new tariffs on Mexico, Canada and China. 

The White House announced Friday that in response to an ‘invasion of illegal fentanyl’ to the U.S., it would impose a 25% tariff on all goods entering the United States from Mexico and Canada, a 10% tariff on Canadian energy and a 10% tariff on all goods entering the U.S. from China. 

Tariffs against China went into effect Tuesday, although Trump agreed to push back tariffs against Mexico and Canada by at least one month after discussions with each respective country about securing the border.

As a result, Democratic lawmakers pressed Greer on whether the tariffs were aimed at renegotiating trade issues or about border security. 

Sen. Ron Wyden, D-Ore., said, ‘Donald Trump governs by whim and in trade that hurts American families.’ 

‘His tariff bluff created huge uncertainty that is costing American businesses and putting the global economy on what I would describe as a month to month lease,’ Wyden said. ‘Frankly, my top priority today is to figure out who the hell in the Trump administration is going to be in charge of trade, what they plan to do, and how this sort of bedlam is going to get straightened out.’

Some Republican lawmakers also voiced concerns with Trump’s tariff plans, and Sen. Steve Daines, R-Mont., said that agriculture communities in Montana suffered after Trump imposed tariffs in his first administration. 

Trump acknowledged on Friday the tariffs might result in ‘temporary, short-term disruption.’ But Democrats claim American taxpayers will end up hurting and paying the price. 

According to one Washington think tank, the nonpartisan Peterson Institute for International Economics, these rounds of tariffs are expected to cost U.S. households roughly $1,200 a year annually.

Fox News’ Louis Casiano contributed to this report.