What a mess there are after a party in the Senate Caucas Room last night. Glasses all over the floor, flattened popcorn, cheese sequished into the rug, Sen. Paul Tsongas (D-Mass.) said he'd never seen it so bad.

"Oscar," observed one guest, referring to the "Sesame Street" garbage eater, "would have a field day."

The reason wasn't wildly celebrating senators. Instead it was their children or their constituents' children, never-ending yards of them, invited to a pary held by the consumer group Action for Children's Television. The kids drank apple juice and hit each other. A few feet above them, the lobbying swirled.

"Is this the way they get money from Congress?" asked Anne Gianotti, a visitor from Memphis who got a last-minute invitation from her congressman. "It looks very expensive."

By Capitol Hill party standards it wasn't at least not at $1,500 that included food and free top-kid entertainment like Slim Goodbody from "Captain Kangaroo" and Mr. McFeely/Speedy Delivery from "Mister Rogers' Neighborhood."

And Susan, from "Sesame Street," who told everybody that Kermit the Frog is running for president. "Miss Piggy might be first lady," she explained. No reaction from the kids. Not much reaction from their parents either, who kept eating popcorn and drinking wine.

The wine was free, as it turned out. Invitations had read "cash bar," but that was before ACT President Peggy Charren found out you can't have cash bars anywhere in Hill office buildings. It's something nobody much complains about.

The party, whose guests included Sen. Bill Bradley (D-N.J.), at least one FCC commissioner, and the Purple Panda, was billed as the gala reception for ACT's eighth annual national symposium. This year, it's entitled "Children and Television: The Health Connection." That means two days of speakers, lunches and panels at the Shoreham-Americana.

"There's such a big problem of health in this country," said Charren. "This is a nice forum for discussion."

Most of the kids at the party, about 150 or so, seemed generally impressed with the spread.

Marcus Miller, the 7-year-old son of a Washington lawyer, said it actually tied for first place as the best party he has ever attended. The other one was a pre-wedding celebration for his teacher. "The only thing better," he explained, "was that I knew everybody there."

Not all were as pleased. "I had to come because I had to watch my sisters," said Steven Whittaker, 12, the son of Rep. Bob Whittaker (R-Kan.). "I usually like staying home watching TV or something."