The street turmoil that swept Kenya’s capital on Tuesday represented a blow to the Biden administration’s tight embrace of President William Ruto, a strong U.S. ally on a continent where American influence is rapidly waning.

Just a day earlier, President Biden had formally named Kenya a major non-NATO ally, and Mr. Ruto had seen off a first group of 400 Kenyan police officers headed to Haiti on a contentious security mission that is largely financed by the United States.

The non-NATO ally designation, which clears the way for greater security cooperation between Kenya and the United States, was one of the main outcomes of Mr. Ruto’s state visit to Washington last month, the first by an African leader in 16 years. At the White House, the Kenyan leader was feted with a state dinner that included celebrity guests and former President Barack Obama, whose father was Kenyan.

For Mr. Ruto, the state visit was the high point of a globe-trotting presidency. He has visited dozens of countries since being declared the winner of a fiercely contested presidential election in August 2022. For the Biden administration, it was an opportunity to cement a major relationship in Africa at a time when rivals like Russia and China have expanded their influence.

However, Mr. Ruto’s domestic support has plummeted over tough economic measures that he said were necessary to get Kenya’s ailing national finances back on track. Many Kenyans, particularly from the middle classes, felt they were being forced to pay more than their fair share — especially as Mr. Ruto’s government showed few signs of cracking down on the top level corruption that has plagued Kenyan governments for decades.

The discontent set off days of protests that reached a nadir with the turmoil on Tuesday, when police fired tear gas and weapons during protests near Parliament in Nairobi. Amnesty International and several civic groups said that at least five people were killed.