As stock markets tumbled the day after the unexpected vote, Obama offered words of calm and continuity, saying the the shocking vote would disrupt neither the “enduring” bond between the U.S. and the U.K. nor American support for the European alliance. In a blitz of phone calls, Obama and his senior advisers called British and European officials to express support. Obama spoke with Prime Minister David Cameron and German Chancellor Angela Merkel separately to begin discussions on how Britain will extricate itself from the 27-member union, a process expected to take up to 2 years. Obama said he came away from his call with Cameron “confident” that Britain is “committed to an orderly transition.”

“One thing that will not change is the special relationship,” between the U.S. and the U.K., Obama said in remarks at Stanford University.

The reassurance could not paper over what was clearly a blow to the president, who in one night saw his calls for unity rejected and his legacy in Europe reshaped. Obama had strongly urged that the U.K. remain in the EU, and the decision significantly undermined his efforts to counter the isolationist viewpoints taking hold in many parts of the world. The vote also ensured that, despite his high-profile aim of strengthening international alliances, he will leave office with the European Union diminished and under threat of further unraveling.

The impact of the vote was felt far beyond London and Brussels on Friday. Stocks plunged in the U.S. and worldwide as stunned investors wondered what will come next for Britain, Europe, the world’s largest economic bloc, and the global economy. U.S. Treasury Sec. Jacob Lew promised to work closely with British and European officials to ensure “economic stability, security, and prosperity in Europe and beyond.”

Lew said he had been consulting for weeks with finance officials and investment firms.

“The U.K. and other policymakers have the tools necessary to support financial stability,” he said.

In the run up to the vote, the White House had declined to discuss its contingency planning for Britain’s departure, suggesting it was not expecting to need it.

But in making his case against the split, Obama had described some stark outcomes. On national security and economic matters, Britain is key liaison to Europe for the U.S. and powerbroker. That status would be diminished upon a withdrawal from the union, Obama said during an April visit to London where he made an aggressive case against the “leave” campaign. Obama also painted a grim picture for British companies that do business with the U.S. The United States will continue to prioritize its still-unfinished free trade deal with the EU and would be in no hurry to start negotiating a free trade deal with Britain.

“The U.K. is going to be in the back of the queue,” he said.

In a statement issued as he traveled in California, Obama took a softer tone.

“The United Kingdom’s membership in NATO remains a vital cornerstone of U.S. foreign, security, and economic policy,” Obama said in a statement. “So, too, is our relationship with the European Union, which has done so much to promote stability, stimulate economic growth, and foster the spread of democratic values and ideals across the continent and beyond.”

U.S. Vice President Joe Biden, traveling in Dublin, added that the U.S. will keep working with its partners to create “a new road ahead.”

House Speaker Paul Ryan said the vote was “all the more reason for America to lead.”

“America needs to lead; the world wants America to lead,” Ryan told reporters in the Capitol.