Foreign policy conservatives said they were impressed by Rubio’s ability to speak in detail on a wide range of issues while avoiding pitfalls that have tripped up some other Republicans.

“It felt as if he were taking a Ph.D. oral exam in foreign policy—and he passed easily,” said Max Boot, a fellow at the Council of Foreign Relations who has provided advice to Rubio and other candidates in an unofficial capacity. “He never seemed the slightest bit flustered, he always had cogent points to make, and he had a plethora of specific facts to cite in his answers about everything from Iraq to China.”

“What most presidential candidates do is just kind of summarize past foreign policy crises to give a Wikipedia page [explanation] of what’s going on,” said Richard Grenell, the former U.S. spokesperson for the United Nations. “Marco Rubio is actually offering solutions and he’s leading the discussion.”

Rubio argued in his speech for U.S. global leadership and a foreign policy based on both national security interests and democratic ideals.

“I believe mankind remains afflicted, and that its destiny remains in our hands,” said Rubio. “And I believe America will continue to advance the cause of peace and freedom in our time.”