Patriots quarterback Tom Brady in the “tuck rule” game (AP Photo/Elise Amendola)

Update, 10:12 p.m.: The owners met until a little before 6 p.m. local time without taking a vote Tuesday on the tuck rule or the helmet proposal

Mara said he thinks the helmet proposal has “a pretty decent chance of passing” Wednesday. But he also did not rule out the possibilities of the proposal being modified or a vote being put off until the May owners’ meeting.

Original post: The NFL is expected to eliminate its infamous “tuck rule” Wednesday, but questions raised by coaches about a proposed ban on some hits delivered with the crown of the helmet are complicating plans to vote on that measure, according to New York Giants owner John Mara.

Mara, a member of the NFL’s competition committee, said Tuesday that “the concern, I think, from a lot of coaches is how it would be officiated.  Some of them think it’s too tough a burden to place on the officials.”

At the annual league meeting in Phoenix, owners approved two lower-profile safety measures Tuesday. One covered defensive formations on field goals and extra points and the other outlawed some “peel-back” blocks.

But after the competition committee presented its proposed rule changes to the owners Tuesday, no votes were immediately taken on the two highest-profile proposals.

The committee has proposed to eliminate the tuck rule, which helped the New England Patriots beat the Oakland Raiders in a 2002 AFC playoff game. It appears that proposal will have little problem generating the 24 votes needed from among the 32 owners to be ratified. It would take effect in the 2013 season.

“That will pass,” Mara said.

Under the new rule, a fumble would be ruled if a quarterback loses the ball after finishing his throwing motion and pulling the ball back down. Under the current tuck rule, such a play is called an incompletion until the quarterback tucks the ball back into his body to become a runner.

Under either rule, it is an incompletion if the quarterback loses the ball with his arm in the throwing motion.

The tuck rule overturned a would-be fumble by Patriots quarterback Tom Brady in the 2002 playoff game. Former Raiders executive Bruce Allen, now the general manager of the Redskins, stood up during Tuesday’s meeting and, in an obvious reference to the Brady play, asked what the call would be if the quarterback has two hands on the ball and loses it, according to one person who was in the meeting room.

The competition committee also has proposed making it illegal for a ball carrier or a tackler to initiate a forceful blow with the crown of the helmet when outside the tackle box (the area between the two offensive tackles) and more than three yards from the line of scrimmage. It would result in a 15-yard penalty when a runner lowers his head into a defender to deliver a blow.

The measure has drawn some criticism from players. Chicago Bears running back Matt Forte was particularly critical on Twitter over the weekend. Competition committee members have called the proposal a common sense safety measure that won’t keep running backs from protecting themselves.

But coaches expressed concerns, according to Mara, about how difficult it will be for officials to determine during games, at full speed, whether such a blow has occurred. Mara said it’s possible that the proposal will be modified, perhaps to make such hits subject to fines by the league but not penalties during games.

“The officials we spoke to,” Mara said, referring to members of the competition committee, “thought it could be officiated.”

Earlier Tuesday at the AFC coaches breakfast, Baltimore Ravens Coach John Harbaugh expressed support for the proposal, saying that hits delivered with the crown of a player’s helmet have no place in football. But Harbaugh also said: “In all fairness, it’s going to be tough on the officials.”