THE TRANSFORMATION TRAP Mr. Obama positioned himself as a transformational leader, but in foreign affairs, as in domestic policy, he overestimated the degree to which the mere fact of his election could achieve that transformation. He has run up against the realities of a chaotic and increasingly multipolar world. As a senator running for president in 2008, Mr. Obama spoke of a “new strategy for a new world” that focused on nuclear disarmament and ending the wars in Iraq and Afghanistan, but also promised the United States is “ready to lead again.” When he won his premature Nobel Peace Prize in 2009, Mr. Obama explained his belief in just wars, including those waged on humanitarian grounds.

It is tempting to dismiss criticism from right-wing Republicans like Senator Ted Cruz, who knows little about foreign policy; from Senator John McCain, who knows quite a lot but advocates a military response to almost every crisis; and from former Bush officials. They have an interest in seeing this president fail. It was disquieting to hear some Republicans speak almost admiringly about Vladimir Putin’s macho boldness when the Russian president invaded Crimea. There was a time when both political parties saw real value in cooperating to advance America’s security interests, and the country was better for it.

But there is also powerful criticism from Democrats, liberals and centrists, who fault Mr. Obama’s handling of Syria (some want airstrikes, some want more weapons for rebels) and Ukraine (many want weapons for the government). His critics are inconsistent in their philosophies and have failed to offer cogent alternatives to Mr. Obama’s policies. But the perception — of weakness, dithering, inaction, there are many names for it — has indisputably had a negative effect on Mr. Obama’s global standing.