U.S. evangelical leaders have joined Pope Francis and other Christian leaders in voicing their concern about the possibility of a U.S. attack on Syria.

The U.S. Congress is currently debating the request of the administration to President Barack Obama to back his plans to launch a military strike on the regime of President Bashar al-Assad in response to a chemical attack carried out in Syria on August 21.

Hundreds died in the attack, including women and children.

In a survey of American evangelical leaders, 62 percent opposed the proposed retaliation against the Syrian government. Only 37 percent were in favor of it.

Leith Anderson, president of the National Evangelical Association (NAE) said he was surprised at the vote.

"I was surprised because I expected the answers would be the other way around," he said in a statement released on the NAE website.

"What we don't know is whether a military attack on Syria would help or hurt Syria's neighbor nations from Turkey to Israel and beyond," said Anderson.

"Some think that doing nothing will communicate weakness and put neighbor nations at greater risk. Others think that Syria might respond to a U.S. attack with its own attack and provoke an explosive regional war throughout the Middle East. We just can't know in advance what might happen."

The NAE represents 45,000 local churches in the U.S. and 40 different denominations.

There is a growing concern among Christian leaders around the world over the effects of American military action in Syria.

Pope Francis said this week that such a move by the United States would be "futile." He has called for Catholics to pray for the Syrian conflict on Saturday, September 7.

Two leaders of the U.S. bishops' conference have urged President Obama to seek a political solution in Syria.

In a letter released on Wednesday, Cardinal Timothy M. Dolan, president of the U.S. Conference of Catholic Bishops, and Bishop Richard E. Pates chairman of the committee on international justice and peace wrote, "We have heard the urgent calls of the successor of St Peter, Pope Francis, and our suffering brother bishops of the venerable and ancient Christian communities of the Middle East.

"As one, they beg the international community not to resort to military intervention in Syria."

The two Catholic prelates urged Obama to shun military options, saying an attack "will be counterproductive, will exacerbate an already deadly situation and will have unintended negative consequences."

Geoff Tunnicliffe, CEO of the World Evangelical Alliance (WEA), said in a letter to the U.S. State Department, the United Nations Security Council and President Obama that Christian leaders in the Middle East also oppose a military strike.

"There is major consensus amongst the Christian leaders in this region that any military intervention would have a detrimental effect ... on Christians in Syria," he said.

Tunnicliffe was at a meeting of Christian leaders in Jordan which included California pastor Rick Warren and Arab Christians

Also at the conference was actress Roma Downey and her husband Mark Barnett, creators of the hit series "The Bible."

"I couldn't find a Christian leader at the conference who supported military intervention," Tunnicliffe said. "The question is, how do you protect Christians if there's a regime change?"

On Tuesday while condemning all use of chemical weapons in Syria, the World Council of Churches general secretary Rev. Olav Fykse Tveit said, "We must do everything possible to starve the fire of war rather than feeding it with further deadly armaments."