WASHINGTON — First, if you’re coming to Washington this weekend for the inauguration, add one more party to your list. If you can handle another one.

That would be a reception hosted by Sen. Claire McCaskill on Saturday afternoon from 2-4 in her office in the Hart Building on Capitol Hill. Cookies, punch and hot chocolate. (Good thing that’s all because you’ll need to pace yourself.) 

Of course, McCaskill might be a tad frantic considering that she has, oh, 20 or so family members arriving for the festivities, including her 80-year-old mother, Betty Anne, who sounds prepared to do the town.

“I’m a little worried about the logistics of everything. I affectionally call my family the Griswolds,” she joked, referring to that Chevy Chase-led film family that had more than a few misadventures in its travels.

McCaskill might not see a whole lot of her kin given her responsibilities as one of the honorary co-chairs of the Presidential Inaugural Committee. 

Of course, she’ll be moving around DC (if that’s possible with so many roads closed) giving “high-fives” to people who helped elect Barack Obama.

She disclosed this morning that one of her duties will be MC-ing a quite exclusive dinner on Monday night honoring Gen. Colin Powell, the former secretary of state and Republican who endorsed Obama’s candidacy.

Then on the Big Day, Tuesday, Jan. 20, she will be part of the tiny gathering at a prayer service just prior to Obama’s swearing-in.

“Those are obviously two things that millions of people would love to have the opportunity to be in,” she said. “I’m thrilled.”