Updated at 11:14 a.m. with mention of liquor privatization initiative.

Republican Attorney General Rob McKenna's gubernatorial campaign got a $5,000 boost this month from a wealthy Medina business executive and his wife.

That wouldn't be so unusual -- except that the couple is Costco co-founder Jeff Brotman, pictured at right, and his wife, philanthropist Susan Brotman -- long known as among the state's most generous benefactors for Democrats.

The Brotmans hosted President Obama at their house for a $17,900 a person fundraiser in February. Susan Brotman is credited with raising $427,150 for Obama's reelection effort.

Their giving to state political candidates also has leaned very heavily Democratic, according to Public Disclosure Commission records.

Between 2004 and 2012, the Brotmans gave more than $10,000 to Gov. Chris Gregoire's various gubernatorial campaigns -- and none to her two-time Republican challenger Dino Rossi.

But here they are, giving $5,000 to McKenna, who hopes to become the first Republican governor of Washington in nearly three decades.

The money -- two $1,800 donations from Jeff Brotman and a $1,400 contribution from Susan Brotman -- came in June 13, according to a PDC report filed by the McKenna campaign last week.

So far, the Brotmans have given nothing to Democratic gubernatorial candidate Jay Inslee, according to the PDC. (Though they had donated to some of Inslee's earlier congressional campaigns.)

Reached by phone, Jeff Brotman declined to discuss the reason for his McKenna donations, calling it "a completely private matter."

One possible explanation: Brotman is a former president of the University of Washington's Board of Regents. McKenna has made increased higher education funding a big part of his campaign for governor.

Indeed, Randy Pepple, McKenna's campaign manager said Jeff Brotman recently met with McKenna over breakfast to discuss his education proposals.

Also worth remembering: McKenna supported Costco's liquor privatization initiative. Inslee opposed it.