SAN FRANCISCO/WASHINGTON (Reuters) - Uber Technologies Inc Chief Executive Officer Travis Kalanick quit President Donald Trump’s business advisory group on Thursday amid mounting pressure from activists and employees who oppose the administration’s immigration policies.

Critics included Uber drivers, many of whom are immigrants themselves.

“Joining the group was not meant to be an endorsement of the president or his agenda but unfortunately it has been misinterpreted to be exactly that,” Kalanick, who had planned to attend a meeting of the group on Friday, said in an email to staff that was seen by Reuters.

Uber spokeswoman Chelsea Kohler later confirmed that he had left the group.

Social media campaigns had targeted Uber, urging users to delete accounts and opt for rival Lyft Inc. Uber has been emailing users who deleted their accounts to say it shares their concerns and will compensate drivers affected by the ban.

Kalanick said he spoke briefly to Trump about the immigration order “and its issues for our community” and told the president he would not join the economic council.

The CEO came under increasing pressure to leave the council after Trump issued an executive order temporarily barring people from seven majority-Muslim nations from entering the United States.

Uber CEO Travis Kalanick attends the summer World Economic Forum in Tianjin, China, June 26, 2016. REUTERS/Shu Zhang

“There are many ways we will continue to advocate for just change on immigration but staying on the council was going to get in the way of that. The executive order is hurting many people in communities all across America,” he wrote in a note to employees. “Families are being separated, people are stranded overseas and there’s a growing fear the U.S. is no longer a place that welcomes immigrants.”

The White House said in a statement Thursday evening that did not mention Uber that Trump “understands the importance of an open dialogue with fellow business leaders to discuss how to best make our nation’s economy stronger.”

The move could put pressure on other CEOs expected to attend a meeting with Trump on Friday. General Motors Co said its chief executive would attend, while Walt Disney Co said earlier Thursday its chief executive would not attend because of a long-planned board meeting.

Others expected to take part include the CEOs of JPMorgan Chase & Co, Blackstone Group LP, IBM Corp and Wal-Mart Stores Inc. Others that are part of the council include Tesla Inc CEO Elon Musk, PepsiCo Inc CEO Indra Nooyi and Boston Consulting Group CEO Rich Lesser.

Musk said he would attend the meeting. “In tomorrow’s meeting, I and others will express our objections to the recent executive order on immigration and offer suggestions for changes to the policy,” he said in a tweet on Thursday.

Kalanick’s departure could signal a growing rift between technology companies and Washington.

“There is a battle brewing between Trump and Silicon Valley,” said Neeraj Agrawal, general partner at Battery Ventures. “They (the Trump administration) clearly don’t value the economic activity generated by tech.”

Microsoft Corp on Thursday said it proposed a modification of Trump’s travel limits.

Technology companies including Microsoft, Google owner Alphabet Inc, Apple Inc and Amazon.com Inc have opposed Trump’s order, arguing that they rely on workers from around the world.

Amazon and Expedia Inc have filed court documents supporting a legal challenge to the order by the Washington state attorney general.