But a growing number of Congressional members were beginning to question the administration’s strategy by the end of the week. And an NBC News poll released Friday morning showed that nearly 80 percent of Americans agreed that the president should seek approval in advance of taking military action.

Officials said Obama also was influenced by Thursday’s lively debate in the House of Commons, where Prime Minister David Cameron lost a vote in Parliament to authorize participation in an allied strike against Syria. Cameron had been a staunch advocate of military action but was chastened in the wake of the vote. “It is clear to me that the British Parliament, reflecting the views of the British people, does not want to see British military action,” Cameron said. “I get that, and the government will act accordingly.”

While Obama’s advisers argued Friday night in private that the humiliating defeat for Cameron starkly illustrated the risks of asking for congressional input, the president responded that the vote in Parliament demonstrated exactly why he should seek a vote on this side of the Atlantic, senior officials told NBC News.