Lawmakers better muster some bipartisan Nattitude. (Toni L. Sandys/Post)

Ask old-timers why Congress is so divisive these days, and many will say it’s because lawmakers of opposing parties rarely hang out and socialize together like they did in days of yore.

Harkening back to an earlier era, members of Congress are planning a bipartisan evening at Nationals Park, where on June 5, they’ll leave politics aside and take in a game between the New York Mets and the Nats.

While we can’t guarantee that there won’t be some friction between, say, Del. Eleanor Holmes Norton and fanatic Mets boosters like Rep. Eliot Engel (D-N.Y.), the event’s fare is more likely to include hot dogs and beer than the usual political bickering.

Reps. David McKinley (R-W. Va) and Diana DeGette (D-Colo.) are organizing the event, which will include a reception before the game (at which the only rule is “no talking about work”), the Capitol Police Honor Guard presenting the flag, and a performance of the national anthem by the Congressional Chorus.

McKinley had initially hoped to throw a bipartisan holiday party, but the “fiscal cliff” negotiations at the end of last year ensured that no one had time for such a fete — not to mention that few were in a festive mood.

And it looks like their colleagues are now game: McKinley and DeGette initially hoped to get 50 members to sign up for the outing, but they’re already at nearly 100, and the new goal is to get 150 lawmakers to go.

The event benefits the Wounded Warrior project, which helps injured veterans transition to civilian life.

And as if you needed more evidence that it won’t be business as usual, the lawmakers are paying for the $34 tickets (or $36 for seats in the right-field corner) out of their very own pockets