Preparations were under way on Tuesday for an all-nighter in the Senate, and HOH is perfectly happy to leave all questions of parliamentary procedure (yawn) and policy substance to the experts. Instead, she offers the skinny on what’s really important here. Namely, the cots the Senators will be sleeping on.

Yes, those mattresses make for a great we-mean-business photo op (see above). But, it turns out, very few Members actually planned to crash on the lumpy, twin-sized sleepers more suited to kids at summer camp than Members of the august deliberative body. [IMGCAP(1)]

First, a note on the sleeping accommodations themselves: They belong to the Senate Sergeant-at-Arms, which owns 12-14 metal cots that it stashes in an off-campus storage facility in Cheverly, Md., a Democratic leadership aide says. And further adding to the roughing-it style, the pillows were encased in 200-thread-count cases — considered pretty rough stuff in the world of luxury bedding (though at least the linens were brand new).

But most Senators won’t actually experience a night at Camp Reid themselves, since HOH couldn’t find anyone planning to give the cots a try.

The taller Senators, in particular, were counting on alternate accommodations. Sen. Jon Tester (D-Mont.), who’s a notably beefy 6-foot-1, planned to slip away to his house, conveniently located just four blocks away from the Capitol, to catch some shut-eye. “I’ve got a real bed there,” he tells HOH. And Sen. John Kerry (D-Mass.), a lanky 6-foot-4, also had a strategy for avoiding cot-crashing. “I’ve got a couch in my hideaway,” he said.

Sen. Jay Rockefeller (D-W.Va.), who towers at 6-feet-7-inches tall, was frank with HOH about his inability to sleep on the flimsy beds. “I don’t fit on a cot,” he confessed.

But perhaps even the cot-shunning Senators still will join in for the requisite ghost stories and pillow fights.

All About the Doughnuts. House Republican Conference Chairman Adam Putnam (Fla.) is making the weekly Conference meetings one of the most exclusive gatherings in town by trying out a new rule: No staff allowed.

The Conference office alerted Members via e-mail last week that the Tuesday meeting would be a Members-only affair and that flacks and even senior aides weren’t invited. Putnam said Tuesday that the new velvet-rope policy is simply a new approach to encourage Member dialogue and he plans to hold Members-only meetings “every four to six weeks.” He also quipped that there was a more nefarious reason for barring staff: “They were eating all the doughnuts.”

At least one lawmaker welcomed the news. “I think it’s a good thing,” said Rep. Dan Lungren (R-Calif.), who has developed a bit of a rep for regularly offering motions to kick staff out of the room at the weekly gatherings. “I’ve counted as many as 53 staffers at a meeting,” Lungren said, explaining that he thinks meetings restricted to Members “provide a better environment for Members to speak freely.”

Lungren said it’s not personal. “I don’t like to kick staff out,” he said, acknowledging that it’s unlikely to produce fewer leaks to the press waiting outside. “That would assume Members leak less than staff do.”

Leaders wary of leaks had nothing to worry about Tuesday. “There was no news,” confided one Republican lawmaker who spoke on condition of anonymity. Natch.

Back in the Saddle. Sen. David Vitter (R-La.) continued his Apology ’07 tour on Tuesday, as he made his much-anticipated return to the Senate after confessing that he was the client of an alleged call-girl ring operated by “D.C. Madam” Deborah Jeane Palfrey.

As Vitter kept a low profile in the halls of the Capitol, Senators of both parties almost uniformly deflected questions about their embattled colleague, saying the still-unspecified “very serious sin” the Senator copped to was a family matter.

The Louisianan did address fellow Republicans, though, during the closed-door GOP policy luncheons. Staffers were asked to leave the room while Vitter addressed his colleagues privately, and sources tell HOH that Vitter simply apologized and got a hearty round of applause.

And whatever his indiscretions, Vitter proved that at least when it comes to avoiding the press, he’s a back-door kind of guy, managing to get into and out of the reporter-thronged luncheon using an alternate route.

Nelson Lightens Up. Sen. Ben Nelson (D-Neb.) is back from the dark side. The Senator, whose suddenly darker hair attracted attention last week — thanks to a barbershop visit gone wrong — is now sporting a more natural look.

HOH brought you the story of Nelson’s accidentally over-dyed locks, and she’s now happy to report that the Senator escaped the incident unscathed. Nelson never did locate the product he was searching for to remove errant hair dye, an actual solvent called “Oops,” he tells HOH. Instead, he got rid of the color the old fashioned way: lots of shampoo. “About eight times every shower,” he said.

And he’s not planning any more changes any time soon. “I’m going au naturel,” he vowed.

Gone Fishin’. Former Sen. Ben Nighthorse Campbell might miss his old buddies in the Senate, but he sure doesn’t miss the hours his previous job entailed. The Colorado Republican dropped in on the GOP Conference’s policy luncheon on Tuesday, something he says he does about once a month, to hang with his pals, GOP Sens. Orrin Hatch (Utah) and Ted Stevens (Alaska).

As the Senate was gearing up for an all-nighter and what’s shaping up to be a long summer of work, Campbell tells HOH he couldn’t help but tease his former colleagues by rubbing in his own leisurely pace.

“I know it isn’t very nice of me, but I was telling them about next week, when I’ll be on a houseboat on Lake Meade with my kids and grandkids,” said Campbell, who now works for Holland & Knight. “I miss my friends, but I sure don’t miss the lifestyle.”

Yeah, rub it in, why don’t you, Senator?

Susan Davis contributed to this report.

Please send your hot tips, juicy gossip or comments here.