SEATTLE — In no way did developer Matt Griffin ever consider owning a professional sports franchise.

With the Seattle SuperSonics seemingly destined for Oklahoma City, Griffin and his big-name partners see no other option than to make a huge financial commitment in an attempt to save the Sonics and pro basketball in Seattle.

"Our interest is not necessarily in being an owner, but seeing a team here in Seattle and seeing KeyArena alive," Griffin said yesterday. "If there was a way to do it without having to own the team, that would be terrific. But these are the cards, (and) we have some generous people here in Seattle that are willing to do this."

Making a last-ditch effort to keep the team, the city of Seattle unveiled a $300 million KeyArena renovation plan yesterday, along with the heavy hitters of local business who are willing to provide a significant financial stake.

Griffin and his three partners — Microsoft Corp. chief executive Steve Ballmer, Costco Wholesale Corp. president and CEO Jim Sinegal and wireless entrepreneur John Stanton — have agreed to contribute $150 million to the arena renovation, contingent on the group's ability to purchase the SuperSonics or another NBA franchise. Only recently did the group up its offer from about $75 million.

The group hopes to have a viable option for professional basketball in Seattle on the table when the NBA's board of governors meets next month to vote on SuperSonics owner Clay Bennett's application to relocate the franchise to Oklahoma City at the earliest possible date.

"This particular announcement, we think, is a game-changer," Seattle Mayor Greg Nickels said. "The fact that local investors are willing to step up with the first 50 percent of the money to get this job done, as well as the investment they're going to make in buying a team to begin with, changes the game."

While private investment would cover half the arena upgrades, the plan envisions that the city and state would split the other $150 million. Half would come from the city of Seattle, offset by lease agreements and taxes on the renovated arena.

The other $75 million would come from existing taxes already in place to pay off bonds on the construction of Safeco Field. Those bonds are scheduled to be paid off early, and the KeyArena plan would call for the taxes to remain in place through 2016, when they were set to expire.

The state legislature would have to approve a continuation of the taxes.