(NBC) - Fifty percent of Americans say they oppose the United States taking military action against Syrian President Bashar Assad, and nearly eight-in-10 believe President Barack Obama should receive congressional approval before using any force, according to a new NBC News poll.

Yet the public is more supportive of military action against the Syrian regime when the scope is limited to using cruise missiles launched from U.S. naval ships – 50 percent favor that kind of intervention, while 44 percent oppose it.

The two-day poll was conducted as the Obama administration weighs launching strikes against Syria for the alleged use of chemicals weapons in its violent civil war, as well as amid growing demands by U.S. lawmakers that Congress should have a voice in any debate to authorize force.

On Thursday night, the Obama administration briefed congressional leaders in its effort to make the case for military intervention.

Also on Thursday, Britain's parliament rejected a motion urging an international response to the chemical weapons attacks blamed on the Syrian government.

In this new NBC poll, 50 percent of respondents oppose the United States taking military action in response to Syria's suspected use of chemical weapons, compared with 42 percent who support it.

And 58 percent agree with the statement that the use of chemical weapons by any country violates a "red line" that requires a significant U.S. response, including the possibility of military action.

Still, a whopping 79 percent of respondents – including nearly seven-in-10 Democrats and 90 percent of Republicans – say the president should be required to receive congressional approval before taking any action.

The poll also finds that only 21 percent think taking action against the Syrian government is in the national interest of the United States. By comparison, 33 percent disagree and 45 percent don't know enough to have an opinion.

And just 27 percent say that U.S. military force will improve the situation for Syrian civilians, versus 41 percent who say it won't.

The NBC poll also shows that President Obama's overall job-approval rating has dropped one point since last month to 44 percent, which is tied for his lowest mark in past NBC News/Wall Street Journal surveys.
e gets even lower marks on foreign policy: Just 41 percent approve of his handling of the issue – an all-time low.
And only 35 percent approve of his handling of the situation in Syria.

The NBC poll was conducted Aug. 28-29 of 700 adults (including 210 cell phone-only respondents), and it has a margin of plus-minus 3.7 percentage points.