"All efforts must come together to save the people of Syria from this bloody chain of events," Jarba said today at the U.S. Institute of Peace (USIP). Jarba, who was elected president of the National Coalition for Syrian Revolutionary and Opposition Forces in August, is due to meet President Barack Obama and Secretary of State John Kerry, among others, during a weeklong stay, his first official visit to the U.S.

The Obama administration has sought to shore up the Syrian opposition since peace talks in Geneva with the government of President Bashar al-Assad broke down in February.

"We will always try to reach a political solution," Jarba told the USIP audience. But Geneva "failed, and now we are here in Washington to discuss with our friends how to revive that political solution."

Jarba emphasized several times that the Syrian opposition and the allied Free Syrian Army aren't expecting and don't want American boots on the ground.

"We do not want for Americans to die in Syria as they died in Afghanistan and Iraq," Jarba said. "This is something we never asked for."

But the rebels need more effective weapons to defend against Assad's air force and win the kind of advantage that might drive him back to the bargaining table, Jarba said.

"We hope the American public … will understand our cause," Jarba said, citing the thousands of years of history of the Syrian capital Damascus and its role as home to a range of nationalities, religions and ethnicities that have lived in harmony in the past. "The crisis has become more than we Syrians can handle."

Rebel forces are struggling to hold their own as the government lays siege to cities such as Homs in the country's center. Yesterday, the government allowed Syrian rebels to withdraw from the city center, known as the "core of the revolution," in a deal that also released captive government fighters in Aleppo and Latakia provinces and allowed the delivery of relief supplies to two other areas. Civilians had been evacuated from Homs in February.

Jarba said it was important to make the deal in order to save lives. But he insisted the accounts of the regime's victories are exaggerated and feed into Assad's propaganda. Jarba held out hope that the patience and determination of the rebel fighters will "win back the city, god willing."

More than 150,000 people have been killed in the war that followed what started as a peaceful uprising. The war has extended into its fourth year, with 2.5 million people having fled the country. Two weeks ago, the leaders of five United Nations relief agencies reiterated pleas for access to provide humanitarian aid in besieged cities such as Aleppo and Homs, and for an end to indiscriminate bombings that are killing and maiming civilians.

Still, the Syrian government has announced it will conduct presidential elections in June, and analysts say Assad is sure to win, raising further questions about the opposition's prospects.

The State Department announced this week that the opposition coalition's Washington and New York offices would be given "foreign mission" status and that the U.S. will increase its nonlethal assistance by $27 million to a total of $287 million, according to the Associated Press. The U.S. in December 2012 officially recognized the opposition coalition as the official representative of the Syrian people. Foreign mission status allows the coalition's American offices to use banking and security services, according to CBS News, which cited State Department spokeswoman Marie Harf. The designation doesn't give the opposition access to the closed Syrian Embassy in Washington, nor does it provide diplomatic immunity.

USIP has been working in support of a peaceful democratic transition in Syria since the revolution started in 2011, working with opposition leaders and activists on transition planning, effective local governance and strengthening their ability to respond to the challenges of protracted conflict. Initiatives often are undertaken in partnership with Syrian-led NGOs, such as The Day After Association, which grew out of a USIP-guided transition planning project called The Day After.

"The severity of the humanitarian crisis in Syria continues to shock our hearts and our conscience," said USIP Acting President Kristin Lord. "We're mindful of this every day."

Jarba, who was born in the northern Syrian city of Qamishli and received his law degree from Beirut University, was arrested by Syrian intelligence in the first month of the Syrian revolution in March 2011. He was released that August. It was the second time he had been detained by the government, having been held previously from 1996 to 1998. He has served as the secretariat of the Syrian National Coalition, the predecessor to the current opposition coalition. Jarba helped found the current coalition.

In his address, Jarba sought to dispel notions that the Syrian opposition and its rebel forces are infiltrated by extremists with an ideological goal of establishing an Islamic state in Syria. He said nothing could be further from the truth, and that the moderate rebel forces themselves have fought factions aligned with al-Qaida or similar groups.

"We are not terrorists. We are not mercenaries … We are part of the core of the Syrian people," Jarba said, adding that it is Assad who is terrorizing the population with an Air Force that drops barrel bombs and uses chemical weapons against its people. The U.S. last year forestalled a potential military intervention in the war in favor of an agreement for the regime to give up its chemical weapons. The U.S. says a poison gas attack in a part of Damascus last August killed almost 1,500 people, including more than 400 children.

Jarba's delegation to the U.S. includes General Abdulelah al-Bashir, who formally defected from the Syrian military in 2012 and now serves as chief of staff for the, Supreme Military Council of the Free Syrian Army. Another delegate is Michel Kilo, a Syrian Christian writer and human rights activist who has been arrested by Assad's government several times over the decades for activities such as his central role in the Damascus Declaration of 2005, when he called for "peaceful, gradual," reform "founded on accord, and based on dialogue and recognition of the other."

The delegation also includes Hadi al-Bahra, the opposition's chief negotiator in Geneva and secretary general of the group's political committee. In a panel discussion at USIP in March, Bahra said the opposition is seeking to persuade the Obama administration that it has made progress in reorganizing and unifying its political structure and clearing its military ranks of extremist fighters. He sought to make the case that the rebels now deserve more intensive American assistance.