A US Marine faces possible dismissal after posting critical remarks on Facebook about US President Barack Obama, with a review board recommending a less than honorable discharge.

Sergeant Gary Stein, 26, a nine-year veteran, posted comments on Facebook and other websites calling Obama a coward and "the economic and religious enemy," a Marine Corps board was told during an all-day hearing on Thursday.

Stein had urged Obama's defeat in the November election, writing "screw Obama" in one posting, and had founded a website called Armed Forces Tea Party, apparently in support of the ultra-conservative Tea Party movement.

On one site he sold bumper stickers reading "NOBAMA 2012."

The three-member board meeting at Camp Pendleton, a military base in southern California, announced its decision just after 11:00 pm Thursday (0600 GMT Friday). The final decision will be made by a commanding general.

Stein had no comment after the decision, but Mark Brewer, one of his civilian lawyers, said: "We're disappointed but we're going to keep fighting for this Marine."

During the hearing, Marine lawyers argued that Stein be booted over the remarks about Obama, who is the commander and chief of US armed forces.

"This is what he's putting out to the public, and he's a sergeant of Marines, on active duty," said Captain John Torresala, representing Stein's commander. "How can this not be prejudicial to good order and discipline?"

Stein's lawyers countered that since the comments were made off-duty they are protected under constitutional guarantees of freedom of expression, saying the Marine Corps's own rules on the matter are vague.

They argued that restricting Marines from participating in political discussions essentially reduced them to second-class citizens.

Stein, who served in Iraq, is currently assigned to scheduling rifle ranges at Camp Pendleton. His enlistment is set to end in July, and and he had hoped to reenlist.