In recent decades, many political observers and historians have often lamented the creation of an “imperial presidency” whose power was virtually unchecked by other branches of the government. Concerns along these lines have grown in the last five years as President Obama seemed even less concerned with respecting the limits the Constitution placed on the executive branch than most of his predecessors as he sought to enlarge the scope and the power of the federal government on domestic issues, especially with regard to his signature health care legislation, ObamaCare. But as we have learned in the last week, when it comes to foreign policy this is a president who has gone in a completely different direction.

As John, Peter, and Max noted over the weekend, the president’s vacillation over whether to respond to Syria’s crossing of the “red line” he had enunciated last year over the use of chemical weapons culminated in a last-minute decision to postpone a strike on the Assad regime and to instead wait for unnecessary congressional approval. In doing so, he made a laughingstock of America’s credibility and caused allies and enemies to question whether this administration had the will to act or could be trusted to keep its word. Optimists may say that the president’s efforts to sell Congress on backing his plan for limited strikes as well as the statements of some congressional leaders will undo the damage done by the White House’s Hamlet act. But it must be understood that not even decisive statements, like that of House Speaker John Boehner offering support this morning to the president, cannot save the situation.

The implications of the congressional debate that will ensue on the future of American foreign policy are clear. Given the growth of isolationism on the right and the left, Obama’s decision to punt on Syria has opened the gates for those who have advocated for an American retreat from global responsibilities to gain more influence. Even if, as it is to be hoped, a majority of both houses of Congress vote to back American action in Syria, it’s not likely that the result of what will follow in the coming days will convince the world that America is still prepared to lead. Although there are good reasons to worry about any intervention in Syria, the arguments for inaction are unpersuasive. Given the stakes involved in letting Assad survive in terms of increasing the power of his Iranian and Hezbollah allies and the precedent set in terms of allowing the use of chemical weapons, the case for action in Syria is powerful.

Boehner deserves credit for speaking up after meeting with the president and making it clear the leadership of the House of Representatives is not prepared to bow to the growing chorus of politicians who are more concerned with placing limits on the executive or opposing Obama at every turn than the need to stand up against genocidal dictators. Given the refusal of many Republicans to stand up to the Rand Paul wing of their party, it is refreshing for the normally cautious House speaker to show his willingness to put the national interest above partisan concerns.

But no matter what Boehner or people like John McCain or Peter King say this week, there is no substitute for presidential leadership. As I wrote last week, it is axiomatic that liberal Democrats are far better placed to convince a majority of Americans that military action is needed in any circumstance than a conservative Republican. Though the left is just as uncomfortable with the assertion of American power as many on the right, there is little doubt that the president is far better placed than his predecessor was or any Republican might be to rally the country behind a policy that would draw a line in the sand about weapons of mass destruction. But with Obama faltering, no one should labor under the illusion that a divided Congress can either stiffen his spin or step into the leadership vacuum he has left.

The implications of the president’s bungling of Syria for the Iranian nuclear threat are clear. Even if the president actually does intend to keep his word to prevent Tehran from gaining a nuclear weapon, his ability to deter Iran or to get them to take his threats seriously has been materially damaged in the last month. For all of the often-justified worries about the dangers of an unchecked “imperial presidency,” there is no substitute in our system for a president who is willing to lead in the midst of a foreign crisis. Until President Obama leaves the White House, that is a handicap this nation and the world that looks to the United States for leadership cannot overcome.