As president, Mr. Obama naturally has absorbed most of the criticism, accused of being too soft not only in his dealings with Mr. Putin of Russia, but also with Syria, Iran and other rogue players on the world stage. The coincidental timing of his proposal to slash the Army to pre-World War II size only gave additional ammunition to the hawks. And some made sure to put former Secretary of State Hillary Rodham Clinton in the cross hairs as well, recognizing her possible presidential campaign in 2016.
"This is the ultimate result of a feckless foreign policy," Senator John McCain, Republican of Arizona, told a conservative political group.
Senator Mitch McConnell of Kentucky, the Republican leader, said on the Senate floor, "The president has eroded American credibility in the world."
Most provocative, perhaps, was Senator Lindsey Graham, who faces aRepublican primary challenge from the right in South Carolina. He traced the Ukrainian crisis to the 2012 attack on the United States diplomatic post in Benghazi, Libya, that killed the envoy to Libya and three other Americans. "It started with Benghazi," Mr. Graham said on Twitter. "When you kill Americans and nobody pays a price, you invite this type of aggression." He added in another post: "Putin basically came to the conclusion after Benghazi, Syria, Egypt — everything Obama has been engaged in — he's a weak indecisive leader."
(Read more: Why Crimea matters)
The White House fired back. "GOP criticism of Pres Obama jumped the shark today when they started saying Benghazi is one of the reasons for what is happening in Crimea," Dan Pfeiffer, the president's senior adviser, wrote on Twitter.
The emerging critique has clearly gotten under the president's skin as well. Without waiting to be asked, he rebutted the idea that Mr. Putin had gotten the upper hand. "I would also note just the way that some of this has been reported, that there's a suggestion somehow that the Russian actions have been clever strategically," Mr. Obama said Tuesday. "I actually think that this has not been a sign of strength but rather is a reflection that countries near Russia have deep concerns and suspicions about this kind of meddling."
The case against Mr. Obama has been building for years. Critics accuse him of caving in to Russia by recalibrating plans for missile defense in Europe and focusing too much on trying to repair relations with Moscow. They point to Syria and the "red line" he warned President Bashar al-Assad not to cross by using chemical weapons as well as his failure to follow through with a planned retaliatory strike.