US President Donald Trump has flagged more tariff pain for Australia, with a “major” expansion of his trade war – as he boasted about world leaders grovelling for exemptions.

In a televised speech to a Republic event on Tuesday (local time), Trump took aim at subsidised medicine schemes such as Australia’s Pharmaceutical Benefits Scheme, which limit the price US drugmakers can charge for their products in some countries.

He flagged pharmaceuticals as next on the US’s hit list for trade hits.

“We are going to tariff our pharmaceuticals, and once we do that they’re going to come rushing back into our country because we’re the big market,” he said.

“We’re going to be announcing shortly a major tariff on pharmaceuticals, and when they hear that they will leave China, and they will leave other places because more of the product is here.”

As more tariffs came into effect at 2pm Wednesday Australian time – including a 104 per cent hit to Chinese goods – Trump said foreign leaders were essentially grovelling to him.

“These countries are calling us up. Kissing my ass. They are dying to make a deal,” he said.

“[They’re saying] ‘please, please sir, make a deal. I’ll do anything sir’.”

The White House has scheduled talks with South Korea and Japan, two close allies and major trading partners, and Italian Prime Minister Giorgia Meloni is due to visit next week.

It has also made clear the door for trade negotiations remains wide open — although exactly how an exemption might be earned remains unclear.

Earlier, Australia was at the centre of a fiery exchange in the US Senate over Trump’s decision to impose a 10 per cent tariff.

Democratic Senator Mark Warner asked US trade representative Jamieson Greer about why Australia –  “an incredibly important national security partner” – had been “whacked” with a 10 per cent hit in last week’s “liberation day” announcement.

“We already have a free trade agreement,” Warner said at a Senate finance committee hearing, describing the move as “ridiculous and extraordinary”.

“We have a trade surplus. So getting the least bad – why did they get whacked with a tariff in the first place?”

Prime Minister Anthony Albanese said the comments echoed what he had said directly to Trump.

“The United States has a trade surplus with Australia, of around two to one. They’ve had that since the Truman presidency, and therefore not only is it an act of economic self-harm for the United States, but it certainly is not an appropriate action and it certainly isn’t reciprocal that Australia has received a 10 per cent tariff,” he said.

But US Trade Representative Jamieson Greer defended the decision, citing Australia’s biosecurity-related ban on imports of US beef and pork.

“Australia has the lowest rate available under the new program,” Greer said.

“We’re addressing the $1.2 trillion deficit — the largest in human history — that president [Joe] Biden left us with. We should be running up the score in Australia.

“Despite the agreement, they ban our beef, they ban our pork.”

Australia has restricted entry of US beef due to mad cow disease concerns for more than two decades, stopping almost all shipments. Earlier in the hearing, Greer called the restrictions “specious, fake science grounds”.

He also told senators that negotiations with countries seeking to lower the reciprocal tariffs announced by Trump last week would proceed country by country.

Greer, who is responsible for implementing tariffs, is the first official to face the US Congress since last week’s global tariff announcement. He said Trump told him no tariff exemptions were planned in the near term.

Greer said he had already engaged with about 50 countries and the “good news” was that most had not indicated they would increase retaliatory tariffs on the US.

But Warner was unmoved, accusing Greer of dodging the central issue and harming key alliances.

“The idea that we are going to whack friend and foe alike — and particularly friends — with this level [of tariffs] is both insulting the Australians, undermines our national security, and frankly makes us not a good partner going forward,” he said.

“The lack of trust from friends and allies based upon this ridiculous policy that goes into full effect at midnight tonight is extraordinary.”

Chalmers calls snap meeting

Treasurer Jim Chalmers has called a snap meeting of Australia’s top economic and financial regulators to talk through the impact of Trump’s tariffs.

The high-powered meeting will reportedly take place on Wednesday and include the heads of the central bank and the banking, business and consumer watchdogs, according to Nine media.

“It’s a confidence building measure with the electorate to say, ‘look, we’re getting our best brains together to work out how we diversify our markets, how we adjust our economy, how we get ready for this’,” ex-ambassador to the US Arthur Sinodinos told Nine’s Today program.

“It’s the sort of thing you’d expect any government to do.”

The heads of the Reserve Bank of Australia, Australian Prudential Regulation Authority, Australian Securities and Investments Commission and Australian Competition and Consumer Commission were expected to be part of the meeting.

-with AAP