Nestled in President Barack Obama's plan to overhaul aspects of the US immigration system are tweaks to rules for high-skilled workers long frustrated with hurdles to getting work or residency approval.

The tech and medical sectors especially have for years complained of difficulties in recruiting talent from overseas, with many potential candidates subject to protracted bureaucratic delays.

"I'll make it easier and faster for high-skilled immigrants, graduates and entrepreneurs to stay and contribute to our economy, as so many business leaders have proposed," the president said during an immigration speech Thursday.

His executive actions, which were immediately blasted by Republicans, garnered most attention for the plan to shield millions of undocumented immigrants from deportation.

Silicon Valley had been hoping for action for high-skilled workers too, but many in the innovative sector felt the proposed changes fell short.

"We appreciate President Obama's efforts to make minor incremental improvements to the high-skilled visa and STEM visa programs and look forward to seeing more details," said Consumer Electronics Association president and CEO Gary Shapiro.

"Still, our high-skilled immigration system needs a complete overhaul, which can't be fixed with an executive action."

He was referring to foreign students studying in the so-called STEM areas of science, technology, engineering and math.

The tech sector has for years lobbied Congress to boost numbers of so-called H-1B visas, which grant skilled workers permission to work in the United States if they are sponsored by an employer.

"Administrative changes on highly skilled immigration can potentially act as a tourniquet to attempt to stanch the loss of foreign talent to other countries. However, we still need the surgery that only Congress can provide to achieve a real recovery," Computer and Communications Industry Association president and CEO Ed Black said in a statement.

Silicon Valley also wants the government to quicken approvals for green cards, which let the holder live in America and are not tied to a particular employer.

Green card quotas haven't increased since 1990 and people from certain countries such as India or China must sometimes wait years. Only a new law can change the situation.

However, the chances are slim of significant immigration reform being passed in what will soon be a Republican-controlled Congress.

- Shortage in the health sector -

Currently, STEM graduates can stay in the United States for 29 months without needing a work visa or a green card, but this will be extended, thus boosting their long-term employment prospects.

Qualified foreigners waiting for green cards will also be allowed to change jobs, a move aimed at encouraging fluidity in the employment market.

Finally, entrepreneurs should be able to more easily obtain visas to launch a business in the United States.

Still, for some the changes don't get to the heart of the issue.

"There are a couple of things they could have done to reduce green card lines, but chose not to do," immigration lawyer Greg Siskind told AFP.

"The long, long wait for green cards is not going to go away."

About a million green cards are handed out annually.

In 2013, only 16 percent were given for job reasons, the rest were reserved for reuniting families, for refugees and for asylum seekers, as well as those who won a lottery to live in the United States.

Outside Silicon Valley, the health sector suffers a worker shortage, especially of nurses and general practitioners. The wait for Indian and Pakistani doctors is notoriously long.

Paradoxically, the provisional relief of between four and five million undocumented immigrants under Obama's unilateral action could make things worse because many will be able to work legally and get health insurance through their jobs.

"Now that they'll be legal, it does create an additional strain on our profession, because we are already facing a primary care physician shortage in this country," said Reid Blackwelder, who chairs the board of the American Academy of Family Physicians.