It’s not quite Plan B time for the thousands of foreign nationals living the Silicon Valley dream. But some are already taking steps to prepare for the Donald Trump presidency.

Companies that rely on the ability to hire highly-skilled foreign workers are rethinking their plans. Some are accelerating efforts to apply for green cards for current foreign employees. Entrepreneurs here on visas are wondering if they will be able to stay. Even Canadians, of all people, here thanks to a visa that’s part of the NAFTA trade agreement, are considering whether they need a backup plan.

Yes, the prospect of a Donald Trump administration has upended the plans of many. In Silicon Valley, which relies on a complex mix of highly-skilled technical workers from other countries, foreign investors, and entrepreneurs from around the globe, the president-elect’s focus on immigration during the campaign has set off new rounds of worry and uncertainty.

Since the election, foreign nationals here and those who work with them have described swinging from confidence that not much will change for them to anxiety over what could happen if Trump cracks down on H1-B visas or renegotiates trade agreements.

“There’s a certain hope and confidence that was taken away,” said Karthik Sridhar, an Indian entrepreneur who founded SupplyAI, a software firm, with U.S. headquarters in Palo Alto.

How big is the foreign population here? More than one out of every three people in Silicon Valley is foreign born, according to the Silicon Valley Institute of Regional Studies. Of workers in computer and mathematical fields in the region, 67 percent were born outside the U.S. And immigrants have started more than half of the 87 so-called “unicorns,” startups valued more than $1 billion, according to the National Foundation for American Policy, an immigration research group.

As a result, the Trump win is having an effect even before he takes office. Already, some foreign businesses that were thinking of expanding in the U.S. are holding off, said Romish Badani, chief executive of Bridge US, an immigration legal service provider for tech startups and other industries.

“We’re seeing hesitation,” he said. “Small companies are saying, ‘Maybe hiring foreign talent isn’t worth it at this stage,’ and some foreign entrepreneurs are starting to shy away,” he said. “They say they are going to wait to see how this plays out.”

The uncertainty extends to foreign students hoping to work here on an Optional Practical Training visa after they graduate. They wonder what will happen now that Trump has picked as his attorney general Sen. Jeff Sessions, a strong critic of OPT and other skilled immigration programs.

Still, among some, there’s wishful thinking that Trump will be too busy focused on other parts of the government, or illegal immigration, to zero in on skilled immigration in the tech industry.

There’s also hope that a Trump administration might welcome foreigners who create jobs, rather than do work a U.S. citizen could do. There may be a renewed effort to offer a “startup visa” for foreign entrepreneurs or to expand the number of green cards available for workers here.

“Those who are replacing jobs should be looked at differently than those creating jobs,” said Manan Mehta, the co-founder of Unshackled Ventures, a venture capital firm with a focus on foreign entrepreneurs. Some, including Mehta’s co-founder, are here on H-1B visas, temporary work visas.

“This is still America,” says Mehta. “A business man will be running our country. That may create some good positive stuff.”

The story of Karthik Sridhar, who founded SupplyAI, is illustrative.

He started his company, which serves the retail market, in India. He came to the U.S. on a visitor visa that didn’t allow him to work while he was in the 500 Startups Accelerator program, with the goal of expanding his business here in the US. He recently switched to an L-1 visa, which allows him to be here for a year with the understanding his business will grow and he will create jobs.

So far, his firm has 10 workers, a mixture of people from the U.S., Europe and India.

Even as he gains more U.S. customers, Sridhar said he is exploring setting up an office in Canada in case he can’t stay in the U.S. or needs a contingency if he wants to hire people who can’t come here. His wife is still in India with their 5-year-old daughter. “She is concerned every day,” he said.

One of his entrepreneur friends outside the U.S. decided not to sell his software in the here in person. Instead, he will do his sales calls by phone. “They have changed their business model,” said Sridhar. “That has a long term impact.”

But entrepreneurs are by nature optimists. As Sridhar says, any changes that result from a new administration are “another impediment I need to get over.”