US President Donald Trump is planning to sign an executive order that seeks to make changes to a visa programme that brings in high-skilled workers.

The time-limited H-1B visas for skilled workers, which are sought by Silicon Valley heavyweights, are meant for scientists, engineers and computer programmers, and are an important gateway for many attracted by tech hubs across the country.

But the White House said the programme is undercutting American workers by bringing in cheaper labour and that some tech companies are using it to hire large numbers of workers and drive down wages.

Trump is going to Kenosha, Wisconsin, on Tuesday where he plans to sign an order dubbed "Buy American, Hire American," ordering the Labour, Justice and Homeland Security Departments to propose reforms to the visa programme to prevent immigration fraud and abuse.

Those departments would also be asked to offer changes so that H-1B visas are awarded to the "most-skilled or highest-paid applicants", anonymous officials told the Associated Press news agency.

There are, however, limits to the scope of Trump's action in the absence of a broader legislative plan.

Administration officials said that the order seeks to strengthen requirements that American-made products be used in certain federal construction projects, as well as in various federal transportation grant-funded projects.

The officials said the commerce secretary will review how to close loopholes in enforcing the existing rules and provide recommendations to the president.

The order specifically asks the secretary to review waivers of these rules that exist in free-trade agreements.

'Largely symbolic'

The Trump administration said that if the waivers are not benefiting the US they will be "renegotiated or revoked".

During his campaign, Trump said he supported high-skilled visas but later came out against them.

At one debate, he called for fully ending the programme, saying: "It's very bad for our workers and it's unfair for our workers. And we should end it".

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"I think what we're looking at here is largely symbolic," New York-based lawyer Danielle Mclaughlin told Al Jazeera.

"On April 29, Trump will be 100 days in office, and one of the promises he made was … that he would make sure that Americans were hiring Americans and that they were buying American."

About 85,000 H-1B visas are distributed annually by lottery. Many go to technology companies, which argue that the US has a shortage of skilled technology workers.

The US president cannot, by a simple decree, change the number of visas allocated.

'Transitional step'

But the White House hopes, that signing the decree will build momentum before a possible legislative reform.

"This is a transitional step to get towards a more skilled-based and merit-based version," a White House official told AFP news agency.

"There is a lot we can do administratively, and the rest will be done hopefully legislatively."

Critics say the programme has been hijacked by staffing companies that use the visas to import foreigners who will work for less than Americans.

The staffing companies then sell their services to corporate clients who use them to outsource tech work.

Employers from Walt Disney World to the University of California in San Francisco have laid off their tech employees and replaced them with H-1B visa holders.

The tech industry has argued that the H-1B programme is needed because it encourages students to stay in the US after getting degrees in high-tech specialties, and that they can not always find enough American workers with the skills they need.