UPDATE 3:53 p.m.  -- After repeated media inquiries about investors Mark Burkle and Mark Mastrov, mayor Kevin Johnson held a press conference Wednesday afternoon in which he declined to publicly identify the private equity partners, but hoped to sometime next week.

“The great news is that there is great interest in Sacramento market,” he said. “I want Seattle to know we’re fighting like crazy to keep the team.”

Johnson did say he will speak by phone Thursday with NBA commissioner David Stern to update him on Sacramento’s progress, which he said will be a “competitive and fair” bid now that Hansen has established an “out-of-town” price for the franchise at $525 million.

Asked if the estimated $15 billion net worth of Hansen’s primary partner, Steve Ballmer, CEO of Microsoft, would trump Sacramento’s attempts, Johnson cited the 2010 sale of the Golden Warriors for $450 million to Joe Lacob, whose net worth was considerably less than his rival bidder, software kingpin Larry Ellison of San Jose.

“The deepest pockets,” Johnson said, “don’t always end up the winner.”

Johnson said two more local business people chipped in $1 million each Tuesday night, bringing the grassroots campaign total to $21 million from 21 investors.

The presence of Burkle, 60, who made his fortune in supermarkets after starting as a grocery boy, would force the NBA to take seriously the attempt to keep the Kings in town. Until the deal with Hansen, the Maloofs have steadfastly maintained the club was not for sale. But now that a purchase and sale agreement has been signed, the Maloofs have created something of a bidding war.

11 a.m. Tuesday

The counterpunch from Sacramento grew more serious with a report Wednesday morning that California supermarket tycoon Ron Burkle and Bay Area investor Mark Mastrov are in “serious discussions” to team up on a bid to buy the Kings and partner with the city on a plan to help finance a new downtown sports arena, according to the Sacramento Bee.

The Bee was told by a source late Tuesday that Burkle, for whom Forbes estimated a net worth of $3.1 billion (128th on the magazine’s list of the 400 wealthiest in America)  and Mastrov are committed to keeping the team in Sacramento and building the Kings into a contender. The teaming of Burkle and Mastrov is seen by city officials as a “dream team” counteroffer to Chris Hansen’s $525 million deal accepted by Maloof family to buythe Kings and move the franchise to Seattle.

Burkle, who co-owns the NHL’s Pittsburgh Penguins, has long had an interest in the Kings. The Maloofs previously expressed no interest in Burkle’s offer two years ago for the Kings. Mastrov, the founder of the 24 Hour Fitness chain, made an unsuccessful bid to buy the Golden State Warriors in 2010 and until now had been the only person to publicly express interest in buying the Kings and keeping them here.

The news that Burkle was back in the hunt for the Kings follows an earlier announcement Tuesday by Mayor Kevin Johnson that 20 prominent Sacramentans had agreed to invest $1 million apiece for a minority stake.

Those local investors would partner with deep-pocketed financiers such as Burkle and Mastrov in making a counteroffer.

The purchase offer would be combined with a concrete plan to finance a new downtown sports arena when Johnson makes his pitch to reject the Seattle deal directly to the NBA’s board of governors in mid April. Johnson will also argue his city, with only one pro team, is a more supportive NBA market than Seattle, which already has the Seahawks, Mariners and Sounders, the MLS’s most popular franchise.

Despite national media reports saying the NBA is inclined to approve the sale and relocation of the Kings, Johnson contended Tuesday he thinks Sacramento has a fighting chance.

“Come April or before, we’re going to submit a fair and competitive offer,” the mayor said.

Johnson acknowledged he was playing catch-up to Hansen, who has agreed to buy 65 percent of the Kings owned by the Maloofs and their Oklahoma business partner, Bob Hernreich. The agreement values the Kings franchise at $525 million.

“(The city has) legitimate individuals who are going to be treated very seriously by the league,” sports business consultant Andy Dolich told the Bee. “That is a good piece of news for Sacramento.”

Sacramento developer Larry Kelley, who is one of the 20 local investors introduced earlier in the day by the mayor, reacted enthusiastically when told about the possible Burkle-Mastrov partnership.

“Sounds to me like it’s a great marriage,” said Kelley, who was a Kings limited partner in the 1990s. “They have money, they certainly have high integrity and a reputation for being very good businessmen.”

Said another potential local investor, developer Phil Oates: “I’m doing this for one reason: It’s time to fight.”

Despite the seemingly long odds, Johnson said he was confident that his message would resonate with the NBA.

Johnson also cautioned Seattle fans not to celebrate yet.

“We as a community, we’ve had the emotional roller coaster (of trying to keep the Kings); it’s hard,” the mayor said. “I would hate for them to be misled.”