San Salvador, El Salvador (CNN)-- In the end, President Barack Obama apparently decided that photos of himself touring historic remnants of a collapsed society might not be the best image for a commander in chief fending off charges even from Democrats that his Libya policy is in shambles.

The controversy over the decision to use U.S. military force has gotten so intense that at a news conference here Tuesday, Obama calmly pushed back at his critics by declaring the effort to stem the humanitarian crisis in Libya has paid important dividends by avoiding a massacre of civilians.

 "We have already saved lives," Obama said at a joint news conference here with President Mauricio Funes of El Salvador.

And for the record, White House aides insist the decision to skip a long-scheduled tour of Mayan ruins on Wednesday was merely a "logistical" matter because Obama now has to conduct a secure call with his national security team Wednesday morning before heading back to Washington.

But in fact, Obama has been doing secure calls with Secretary of State Hillary Clinton and other officials throughout this five-day tour of Latin America without any other major disruptions to his schedule.

And scrapping the tourist stop will only get Obama back to Washington a couple of hours earlier than expected anyway -- so why all the fuss?

The difference-maker may have been the fact that after days of White House aides insisting this swing through Latin America was not a distraction, Obama found himself particularly on the defensive on day four of the trip.

First aboard Air Force One on his way here from Santiago, Chile, Obama had to make phone calls to British Prime Minister David Cameron and French President Nicolas Sarkozy to try to clear up confusion about whether the United States is going to be able to hand off responsibility for policing the no-fly zone to key allies.

Then at the news conference here later in the day, Obama faced questions from reporters about whether he adequately prepared the American people before jumping into the difficult mission and whether he could articulate how such an operation is in the national interests of the U.S.

"Where a brutal dictator is threatening his people and saying he will show no mercy and go door-to-door to hunt people down, and we have the capacity to do something about it, it is in our national interest to do so," said Obama.

Clearly aware of the growing disenchantment with the move from fellow Democrats, however, Obama quickly noted it "doesn't mean we can solve every problem in the world."

Those words are not likely to do much back in Washington to calm liberals who are furious at Obama, particularly his decision to move forward with a military engagement without a full debate in Congress.

Four House Democrats fired off a letter to Obama on Tuesday filled with tough words and phrases like "quagmire" and "rush to war" that read more like a missive they would have sent to former President George W. Bush than a Democratic president whose agenda they've supported from top to bottom.

"The United States must immediately shift to end the bombing in Libya," said the letter from Democratic Reps. Raul Grijalva of Arizona, and Mike Honda, Barbara Lee and Lynn Woolsey of California. "Rest assured we will fight in Congress to ensure the United States does not become embroiled in yet another destabilizing military quagmire in Libya with no clear exit plan or diplomatic strategy for peace."

The lawmakers added the U.S. action in Libya "represents a dangerous path toward perpetual U.S. military engagement around the world."

They concluded, "there are serious consequences for rushing to war with a limited understanding of the situation on the ground and no exit strategy or plan -- we learned this lesson through two ill-advised wars in Iraq and Afghanistan."

Obama tried to calm some of those concerns by again repeating that the U.S. will only be in a lead role for "days not weeks" and "there is nothing that has happened over the last several days that changes that."

"It is not going to be our planes maintaining the no-fly zone," added Obama. "It is not going to be our ships that are going to be enforcing the arms embargo."

He said the bottom line is that "it means the United States is not going to be bearing all the cost."

Obama also said that "nobody has a bigger stake" in the outcome of the change happening through the Mideast and North Africa than the United States.

Mentioning the historic transfers of power in Libya's neighbors in Egypt and Tunisia, Obama said it is important that these nations "become models for peaceful transition."

As for the mission in Libya, Obama said, "We need to make sure we see this through effectively."

But the letter from the four House Democrats suggested Obama still has a lot of selling to do even in his own party.

"We have serious concerns about whether or not an effective and thorough case for military intervention in Libya was made," wrote the lawmakers. "Too many questions remain. What is our responsibility now? Do we own the situation in Libya and for how long? Where does this dramatic acceleration of military intervention end?"

Source: http://www.cnn.com/2011/POLITICS/03/22/obama.libya.policy.defense/#