While Seattle leaders scramble to build support for an arena plan to keep the Sonics in town, Oklahoma City voters on Tuesday overwhelmingly embraced a $120 million tax package aimed at luring the team as that city's first major-league sports franchise.

More than 60 percent of Oklahoma City voters favored the 15-month, one-cent sales tax to fix up the city's Ford Center arena and build a new NBA practice facility, according to unofficial final returns from the Oklahoma County Election Board.

Seattle leaders downplayed the result, saying they'll fight to enforce the Sonics' lease at KeyArena while working on an arena package to keep the team in its home of 41 years.

"It really doesn't have a bearing on our dealings with the Sonics," said Marty McOmber, a spokesman for Seattle Mayor Greg Nickels.

Oklahoma City Mayor Mick Cornett declared victory during a vote-watching party at a restaurant in the city's Bricktown entertainment district. "We will not let you down. We know we have some work to do and we'll get to it starting first thing tomorrow morning," Cornett said.

The Oklahoma vote was aimed at sending a powerful signal to the NBA Board of Governors. At its meeting next month, league owners will vote on whether to approve Sonics owner Clay Bennett's request to move the team to his hometown.

Bennett issued a written statement Tuesday praising Oklahoma City voters for "their continued commitment to excellence."

The vote stands in stark contrast to Seattle's only public vote related to the Sonics. Seattle voters in 2006 overwhelmingly approved an initiative to restrict taxpayer subsidies for any arena upgrade for the Sonics or other professional sports teams.

Despite Tuesday's vote, the Sonics' future remains up in the air. The Sonics have a lease at Seattle's KeyArena through September 2010, and the city has sued to keep the team from leaving early.

Brian Robinson, co-founder of the fan group Save our Sonics, said the Oklahoma results won't determine the fate of the Sonics if leaders here come up with a viable arena alternative before the lease runs out.

"This has never been about Seattle versus Oklahoma," Robinson said. "Oklahoma City is likely to get NBA basketball. What we've got to focus on is making sure it's not our team."

Roy Williams, president of the Greater Oklahoma City Chamber, said, "The Sonics are in Seattle, and the Sonics can stay in Seattle. That's in the hands of Seattle. Seattle can still keep their team if they're willing to do what it takes to pay for it.

"It's not ours to win. It's Seattle's to lose."

Oklahoma City's Ford Center opened in 2002 and hosted the New Orleans Hornets for two seasons after Hurricane Katrina. Planned upgrades include restaurants, clubs, suites and new locker rooms.

If no team shifts to Oklahoma City before June 2009, the one-cent sales tax passed by voters runs out after 12 months and the practice facility and any NBA-specific improvements to the Ford Center will not be built.

Cornett said the arena vote would help put Oklahoma City on a world stage. The Greater Oklahoma City Chamber's campaign said the vote was about becoming a "Big League City."

Meanwhile, in Seattle, political and business leaders have been trying to garner support for a $300 million KeyArena expansion they hope could keep the Sonics in the city. The cost would be split 50-50 between taxpayers and a group of local investors said to be willing to buy the Sonics from Bennett.

That group includes Costco CEO Jim Sinegal and Seattle developer Matt Griffin. They are backed by other prominent local business leaders who have not revealed their identities.

Griffin said the Oklahoma City vote does not change the group's strategy because "we assumed it would pass."

But Griffin, who met with Gov. Christine Gregoire and legislative leaders this week, said he did not know whether there would be any movement on a Seattle arena package before the Legislature adjourns next week.

Seattle Times staff reporter Jim Brunner and Associated Press reporter Jeff Latzke contributed to this report.