The White House's tour to sell the Syrian intervention to progressives continued on Friday with a speech by U.N. ambassador Samantha Power to the Center for American Progress.

Power, like Secretary of State John Kerry, focused a good portion of her pitch to the left on the doubts and questions raised about using military force on the country. And, like Kerry, Power's argument weighed those doubts against what she called the "costs of not acting." Those costs, she argued, were heavier than the risks of going ahead with the President's decision. And that scale, according to Power, was in the context of a U.N. that the ambassador carefully characterizes with the following line: "the security council the world needs to deal with the current crisis is not the security council it has." Power tiptoes around an attack on the international organization in order to sell the idea of American intervention as a last resort after all other options are "exhausted." Those exhausted options, in her opinion, include the U.N. and the International Criminal Court. 

John Kerry's interview with MSNBC's Chris Hayes last night was met with some skepticism, and failed to convince Hayes himself of the government's case for intervention. And while today's speech may not be a prime-time feature, it seems to have picked a more sympathetic audience. The president of CAP's action wing is already a strong backer of Syrian intervention (The Atlantic interviewed CAP Action Fund head Tom Perriello earlier this month). CAP president Neera Tanden's introduction to Power's remarks was also sympathetic to the administration's case for intervention. CAP is the parent organization of ThinkProgress, which has published pieces both sympathetic and critical of Obama's decision to strike in recent days. As Slate's Dave Weigel wrote, the pitches seem to aim for a perceived sweet spot between liberal anti-war activism and liberal sympathy for humanitarian intervention — even as the administration emphasizes that the military action they're planning would only be intended to "deter and degrade" Syrian President Bashar al Assad's ability to use more chemical weapons. 

"This is the right debate for us to have. We should be asking the hard questions...there is no risk-free door number two," Power said, adding that she recognizes "how ambivalent Americans are about the situation [in Syria]."

Power's case against that ambivalence relied on two points: first, that Russia wasn't going to allow the U.N. to intervene in Syria in any meaningful way, no matter how much the U.S. would like to use the international body in principle. And second, that the chemical weapon strike in Syria on August 21 represented a unique atrocity that required action by its very nature. To address that second point, Power used an agonizing vignette of a man cradling his two dead daughters, who were dressed in "the pink shorts and leggings of little girls:"

What comes to mind for me is one father in al Ghouta saying goodbye to his two young daughters. His girls had not yet been shrouded, they were still dressed in the pink shorts and leggings of little girls.  The father lifted their lifeless bodies, cradled them, and cried out "Wake up…What would I do without you?… How do I stand this pain?" As a parent, I cannot begin to answer his questions. I cannot begin to imagine what it would be like to feel such searing agony. 

She called that attack causing that pain a "uniquely monstrous crime that has brought us to this crossroads." The vignette, it seems the ambassador hoped, would help to land her argument that those opposed to intervention would regret it later if nothing is done. Non-action would "give a green light to outrages that will threaten our security and haunt our conscience." 

Power also spent substantial time pushing back against the idea of the administration having any other viable option available to them. "We have pursued countless" tools "short of military" force in Syria, she said, none of which prevented the chemical attack in August. "We backed the U.N. diplomatic process," provided more "humanitarian assistance" to Syrian rebels and "worked with the U.N. to create a group of inspectors," she added. But in her opinion, the international body is now "paralyzed" to do anything further.

"Russia, backed by China, has blocked every relevent action in the Security Council," she said, speculating that Assad's calculus before using chemical weapons may have involved the knowledge that Russia would support their ally and veto Security Council resolutions designed to punish or condemn Syria. She gave the example of the council's apparent inability to "put out a press statement" disapproving of the recent attacks. In short, "We would if we could but we can't," Power said of going ahead with U.N. avenues to address the crisis in Syria. 

Hours before Power spoke, President Obama again addressed his decision to seek approval for military force in Syria, and his campaign to win over international support for such a move at this week's G20 Summit