Any political candidate knows to expect attacks — sharp, personal or unfair — from an opponent. But you know things are tough when you get hammered by your own family.

That’s what happened last week when some of Ohio state treasurer and GOP Senate candidate Josh Mandel’s cousins (on his wife’s side) took out a paid ad in the Cleveland Jewish News that blistered and even belittled him for his views on gay marriage and gays in the military.

Mandel married into the prominent, wealthy (think mega-builders) and sprawling Ratner family, nine of whom signed the “Dear Josh” letter.

“Four years ago you came into our family,” they began, and “how happy our family members were as they described it afterwards.

“So we were deeply saddened,” they said, during the Oct. 18 debate with incumbent Democratic Sen. Sherrod Brown, where Mandel talked about his views on those issues.

“Your cousins, Ellen Ratner and Cholene Espinoza,” the letter noted, married in Massachusetts eight years ago, so “it hurts us that you would embrace discrimination against them. ”

“Like you, Cholene spent many years in the armed forces. A graduate of the Air Force Academy . . . she became the second woman in history to fly the U-2 reconnaissance plane. And yet, you have argued that she, like many gay and lesbian soldiers, should be forced to live a life of secrecy and lies.”

Okay. A substantive discussion so far. But then it got tougher.

“This family is sprawling and diverse,” the cousins said, “but it has always believed strongly in the values of equality and inclusiveness. Your discriminatory stance violates these core values of our family.”

Then they twisted the knife. Mandel, though 35, looks like a college kid.

“Nevertheless, we hope that over time, as you advance in years and wisdom, you will come to embrace the values of inclusiveness and equality as well.”

Mandel’s campaign told the Cleveland Plain Dealer that none of the Ratners who signed the letter even live in Ohio.

“Josh has never met any of the ‘cousins’ who signed that letter and has no idea who they are,” a campaign spokesman said. “He looks forward to having the opportunity to meet them someday.”

Not a bad idea since one of them, Bruce Ratner, is an owner of the National Basketball Association’s Brooklyn Nets (formerly based in New Jersey) and builder of the new Barclays Center arena and massive Atlantic Yards complex. Bruce’s brother and co-signee of the letter, is Michael Ratner, longtime head of the Center for Constitutional Rights. (Both the brothers are from Cleveland.)

Phew! Might want to take a pass on that invite to Thanksgiving dinner at the Ratners.

Friends of Bill

Former President Bill Clinton’s enthusiastic embrace of former frenemy President Obama’s reelection bid was much noted.

But less noted was his behind-the-scenes work for his countless close friends running for office. And he has so many, many friends.

For example, we got an e-mail last week from Clinton with the shocking news that his “friend Manan Trivedi’s district is being bombarded with false attack ads from those GOP Super Pacs.”

So “donate $6 or whatever you can,” Clinton wrote, “so he can beat back Karl Rove, the Koch Brothers” and so on.

All the e-mails were pretty much identical: “You know I believe in arithmetic,” they started out, and “the numbers show Democrats are being outspent.” So open your checkbooks.

But some candidates didn’t need as much as others. While his buddy Trivedi, who was running in a rematch against Rep. Jim Gerlach (R-Pa.) needed $6 from you. Others, such as “my friend Dan Maffei” running for a seat he lost in 2010 in Syracuse to Rep. Ann Marie Buerkle or “my friend Suzan DelBene” in a tight race in Washington against John Koster or “my friend Patrick Murphy” running in Florida against Loop Favorite Rep. Allen West (R) only needed three bucks.

That may seem like small change now, but when Hillary runs in 2016 . . .

Double ‘Jeopardy!’

Let it not be said that Sen. Chuck Grassley (R-Iowa) doesn’t pick some pretty smart staff in his Washington office.

In 2004, Tom Walsh, a former longtime Grassley health-care staffer who’s now at the State Department working on AIDS relief programs, set the record at the time for the most consecutive wins on the TV game show “Jeopardy!” winning $184,900.

Last week, Paul Nelson, a legislative correspondent in Grassley’s office here, became the latest champion, winning $14,000 last week and then defending his crown with a $15,200 win in a second appearance that aired Monday in Iowa.

Grassley says he’s not surprised. “Capitol Hill attracts people with intellectual curiosity and a lifelong love of learning. They know how to ask all the right questions.”

And they obviously know the right answers.

With Emily Heil