Donald Trump reiterates 'US govt shutdown' threat if not backed on immigration policies

US President Donald Trump on Tuesday threatened a government shutdown if the US Congress refuses to back major changes to immigration policies like establishing a merit-based system, saying America is the "laughing stock of the world" due to the "worst" immigration laws.

Trump has repeatedly called for the merit-based system and the chain migration to reduce overall immigration to the US. Earlier this year, the White House released a proposal for merit-based immigration, which floundered in Congress amid tepid support from within the president's own party.

He also launched an aggressive push for additional border security measures early this year which include USD 25 billion toward construction of a wall along the US-Mexico border.

"We're the laughing stock of the world. We have the worst immigration laws anywhere in the world," Trump said, adding the US needs border security.

"Border security includes the wall, but it includes many other things. We have to end the lottery. We have to end the chain migration, which is like a disaster. You bring one person in and you end up with 32 people," Trump said at a White House joint news conference with visiting Italian Prime Minister Giuseppe Conte.

US lawmakers face a spending deadline in September. The federal government has already shut down twice this year, first over a failed deal for Dreamers, young undocumented migrants brought to the country as children, then over a funding bill.

A shutdown was avoided in March after Congress approved a USD 1.3 trillion spending package that would fund the government through the end of September. However, the spending measure did not address immigration and Trump said at the time, "I will never sign another bill like this again."

"We have to end these horrible catch-and-release principles where you catch somebody, you take their name and you release them. You don't even know who they are. Then they're supposed to come back to a court case where they want us to hire thousands of judges. The whole thing is ridiculous and we have to change our laws. We do that through Congress," Trump said.

The US president said he and the Italian prime minister are united in their conviction that strong nations must have strong borders.

"We have a solemn obligation to protect our citizens and their quality of life. My administration is working hard to pass border security legislation, improved vetting and establish a merit-based immigration system, which the United States needs very, very importantly, very badly," he said.

In the past also, Trump has favoured a merit-based immigration system which, according to him, would attract the best and the brightest from across the world to the US.

"As far as the border is concerned and personally, if we don't get border security, after many, many years of talk within the United States, I would have no problem doing a shutdown. It's time we had proper border security," he said.

Trump's threat, his second in two days, put him further at odds with his own party in Congress, where many Republicans are facing tough fights in the midterm elections in November.

Trump said he and Conte are focused on the urgent need to protect their nations from terrorism and uncontrolled migration.

"Our countries have learned through hard experience that border security is national security, they are one and the same," he said.

"Like the United States, Italy is currently under enormous strain as a result of illegal immigration, and they've fought it hard and the prime minister frankly is with us today because of illegal immigration. Italy got tired of it, they didn't want it any longer," said the president.

Trump has come under intense criticism for his zero-tolerance immigration policy, which prioritises prosecutions of people who enter the US illegally. That policy led to thousands of children being separated from their parents at the southern border. A federal judge ordered the government last month to swiftly reunite those families.