ORLANDO, Fla. -- The posting-fee system that has allowed Yu Darvish, Ichiro Suzuki, Daisuke Matsuzaka and others to play Major League Baseball before reaching free agency in Japan is in limbo, Rob Manfred, MLB's chief operating officer, said on Thursday.

The impasse between Major League Baseball and Nippon Professional Baseball puts the immediate future of pitcher Masahiro Tanaka in doubt. Tanaka, who went 24-0 in the regular season this year for the Japan Series-champion Rakuten Golden Eagles, was expected to be posted this offseason and command a high fee and multiyear contract.

Without a posting agreement, the 25-year-old Tanaka would have to play two more seasons to attain the nine years of service time required to become a free agent in Japan.

"What I would tell you is that we made a proposal to the Japanese," Manfred said at the end of the year's final quarterly Owners Meetings. "When we made that proposal, we told them it was important that they give us a timely response. Unfortunately, they have not been able to do that."

MLB waited several weeks for approval of its proposal by Japanese baseball officials, but sentiment among a growing number of Major League owners has turned to ending the posting system entirely.

"In today's meeting there was discussion that will require us to go back to the Japanese and have some further conversation about the proposal we made to them," Manfred said. "It sat out there for a long time. They couldn't give us an answer and we're going to have to go back to them and talk to them about where we are right now."

Tanaka is the most sought-after Japanese pitcher since Darvish signed with the Texas Rangers before the 2012 season. Tanaka did not lose a game this season until Game 6 of the Japan Series against the Yomiuri Giants. He came back in Game 7 to pitch a flawless ninth inning in relief and save the series-deciding victory despite having thrown 160 pitches the previous day.

Under the posting system, teams in Japan's Pacific and Central Leagues could post a player with 1-8 years of experience. Major League clubs would make blind bids for the right to negotiate a contract with the player, and the highest bidder would be granted an exclusive window to sign him. If the player signed, his former team in Japan received the posting fee as the purchase price for the player. If a deal was not reached, the player would return to his team, negating the posting fee with no penalty to the MLB team.

Under the most recent proposal, the highest-bidding Major League team would still be awarded exclusive rights to negotiate with a player, but the fee going to the Japanese team would be the average figure of the top two bids, according to a report in The Japan Times. In addition, a team that fails to sign the player during the exclusive negotiating window would be subject to a fine by MLB, the newspaper said.

After lengthy discussion, the Japanese players association reluctantly approved the plan, although the union sought a shortening of the NPB nine-year free agency requirement to something closer to the six years required for a Major League player to reach free agency.

"There was not enough time on our side and we haven't got any more bargaining power than this. It was an agonizing decision [to accept the revisions]," Toru Matsubara, secretary general of the Japan Professional Baseball Players Association, told The Japan Times.

The Japanese clubs are scheduled to vote on the proposal on Monday, but Manfred said, "We got an e-mail from the Japanese this morning saying they're not in a position to give us a formal response."

Manfred was asked if he's concerned about any time constraints.

"To be honest with you, I'm not," he said. "It isn't acceptable from our perspective. The Japanese players association has an agreement with NPB. At a certain point in time, their players become available via free agency. If that's the way we get Japanese professionals, I think the 30 Major League clubs are prepared to live with that result. So I don't feel a lot of pressure in terms of the time."

For Major League clubs, the issue is the expense of both the posting fee and a player's contract. In Darvish's case, Texas paid the Nippon Ham Fighters a record $51.7 million posting fee and signed the right-hander to a six-year, $60 million contract. Prior to the 2007 season, the Boston Red Sox paid the Seibu Lions $51.11 million for the right to sign pitcher Matsuzaka to a six-year, $52 million contract.

In comparison, in 2001, the Seattle Mariners paid what was then a record $13 million posting fee to the Orix BlueWave for the right to sign Suzuki.

Other signings of high-profile Japanese players, such as Hideki Matsui and Koji Uehara, occurred after those players had become free agents, so they did not require the posting process.