If you're wondering why the Senate looked like a  convention of ice cream vendors Thursday, the reason is that it was the one day of the year when senators are encouraged to wear seersucker suits.

Some 20 senators showed up wearing the warm weather garb, including Majority Leader Bill Frist, who not only was wearing seersucker but white shoes as well. Three other senators did the same, including Republicans Gordon Smith of Oregon and Arlen Specter of Pennsylvania, and Democrat Ben Nelson of Nebraska, who was decked out in a bow tie as well.

Specter drew stares in the Senate Dining Room,not only for his unusual attire, but for the fact that he was having lunch with  Supreme Court Associate Justice Clarence Thomas, apparently to discuss judicial nominees coming before his Judiciary Committee.

The two Mississippi Republicans, Trent Lott and Thad Cochrane, looked like they were made to wear seersucker, which they probably do in the hot Mississippi summers.

At least a half-dozen women senators were among the seersucker bridgade, thanks to Democrat Dianne FeinsteinDianne FeinsteinThis week: Congress returns to government shutdown fight Hotel industry details plans to fight Airbnb Congress needs a do-over on fraud-laden 'Immigrant Investor' program MORE of California, who picked up the tab for their suits. They included Democrats Blanche Lincoln of Arkansas and Barbara BoxerBarbara BoxerAnother day, another dollar for retirement advice rip-offs Carly Fiorina 'certainly looking at' Virginia Senate run Top Obama adviser signs with Hollywood talent agency: report MORE of California -- who went only halfway, wearing a seersucker jacket and black slacks; and Republicans Elizabeth Dole of North Carolina and Maine's Olympia Snowe and Susan CollinsSusan CollinsCollins: I'm not working with Freedom Caucus chairman on healthcare Mexico: Recent deportations 'a violation' of US immigration rules White House denies misleading public in aircraft carrier mix-up MORE.

Conspicuous by his decision not to wear seersucker was West Virginia Democraqt Robert Byrd, who had just become the longest serving senator in history.

New Mexico Republican Pete Domenici, asked why he didn't don the hot weather gear, said, "Because I don't have a seersucker suit."

To continue with the ice cream motif, many of the senators joined staffers, lobbyists, journalists and tourists in an ice cream social in the park next to the Russell Office Building later in the day.