Washington (CNN) - Half of all Americans say they oppose possible U.S. military action against Syria, according to a new national poll.
But the NBC News survey suggests support does increase if any such attack is limited to cruise missile launches.
And nearly eight in ten of those questioned in the survey released Friday morning say President Barack Obama should be required to get Congressional approval before launching any military attack against the forces of Syrian President Bashar al-Assad.
The poll, conducted Wednesday and Thursday, indicates 50% of the public says the U.S. should not take military action against Damascus in response to the Syrian government's alleged use of chemical weapons against its own citizens, with 42% saying military action is appropriate.
But the survey suggests that if any military action is confined to air strikes using cruise missiles, support rises. Fifty percent of a smaller sample asked that question say they support such an attack, with 44% opposing a cruise missile attack meant to destroy military units and infrastructure that have been used to carry out chemical attacks.
The president said on Wednesday there's no doubt the Syrian regime launched chemical weapons attacks against its own people. Assad's government has blamed the August 21 attack on rebels.
As the president weighs a military response, top administration officials Thursday evening briefed member of Congress. More than 100 members of Congress are urging the White House "to consult and receive authorization" before launching any military action.
According to the poll, 79% of the public - including nearly seven-in-ten Democrats and 90% of Republicans - say Obama should be required to receive Congressional approval before taking any military action.
The War Powers Resolution passed by Congress in 1973 requires the president seek consent from Congress before force is used, or within 60 days of the start of hostilities. It also says the president must provide Congress with reports throughout the conflict.
Since 1973, the United States has used military force in Grenada in 1983, Panama in 1989, Iraq in 1991, Haiti in 1994 and Kosovo in 1999. In all those instances, presidents - both Democrats and Republicans - sidestepped Congress and committed U.S. military forces without obtaining Congressional approval.
Congress did, however, provide President George W. Bush with its approval for the war in Iraq in 2002 and the war in Afghanistan after the September 11, 2001, terror attacks.
The poll also indicates that just one in five say launching military action against the Syrian government is in the U.S. national interest, with one-third disagreeing and nearly half of those questioned not sure.
Would a military strike make a difference in Syria, which has been ravaged by a bloody civil war between the government in Damascus and various rebel factions? The answer appears to be no, which just 27% saying a U.S. attack will improve the situation for Syrian civilians. Just over four in ten disagree and three in ten aren't sure.
The NBC News poll was conducted August 28-29, with 700 adults nationwide questioned by telephone. The survey's overall sampling error is plus or minus 3.7 percentage points.
CNN's Tom Cohen contributed to this report