NFL teams have proposed nine rule changes for 2019, including an intriguing alternative from the Denver Broncos to bypass the onside kick.

According to the Broncos' proposal, released Friday night by the NFL, each team would have one opportunity per game to remain on offense after a fourth-quarter score. Instead of kicking off, the team would line up at its 35-yard line for what is in essence a fourth-and-15. If the team gains the 15 yards, it maintains possession. If not, the defense takes over.

The NFL annually invites teams to propose rule changes, but the competition committee is charged with vetting and either endorsing or allowing them to stand on their own. Historically, owners defer substantial judgment to the committee, which is scheduled to meet later this month to finalize its recommendations for 2019.

Minnesota's Adam Thielen jumps on an onside kick in a game against the Eagles last season. A proposal by the Denver Broncos would provide teams with an alternative to the onside kick if approved by NFL owners. Andy Lewis/Icon Sportswire

Votes from 24 owners are required to approve any rule changes. The Broncos' submission reflects the increased difficulty of onside kicks under new kickoff rules implemented last season. In 2018, NFL teams recovered only four of 52 onside kicks, according to ESPN Stats & Information.

The new Alliance of American Football, which has outlawed kickoffs, offers teams the chance to convert a fourth-and-12 from its 28 if it is down by 17 points or more in a game or if it is trailing by any deficit with five minutes or less remaining in the fourth quarter.

Of the nine NFL rule change proposals, seven involved expanding replay review. The Washington Redskins, most notably, proposed that all plays be subject to coaches' challenges.

During a meeting last week at the NFL scouting combine, competition committee members expressed deep skepticism about expanding replay. They were slightly less doubtful of another idea suggested by coaches -- to add a "sky judge" to each officiating crew, with the authority to make calls from the press box -- and pledged to study it further this month. The discussion was energized by a missed pass interference call near the end of the NFC Championship Game, won in overtime by the Los Angeles Rams.

Meanwhile, the Kansas City Chiefs followed through on their plans to propose that each team be guaranteed a possession in overtime, regardless of whether a touchdown is scored on the first possession. The Chiefs' proposal would also abolish overtime in the preseason and eliminate the overtime coin toss. Instead, the team that won the pregame coin toss would choose whether it wanted to start overtime with the ball or on defense.