REUTERS/Hyungwon Kang
"It's a terrible thing if Britain leaves," Summers said on a Friday morning panel. "It's a terrible thing for the European Union, which will lose a counterweight to Germany."
Markets and politicians are still digesting the shocking results of yesterday's election results, which defied all pollster predictions.
That has pushed some to speculate that Britain will, in fact, quit the EU (known as the 'Brexit').
Summers also said there would be a substantial impact for Britain.
"It would mark a sharp break in British-European relations," he said, adding that the British would become less relevant to US foreign relations. He said Britain would become "an island nation in the truest sense," adding that a Brexit would "mark the end of a several-hundred year chapter in history where British opinion loomed large on the world stage."
But does he actually think it will happen?
"I would bet right now that five years from now that Britain will remain in the union," he concluded.