WASHINGTON — A historic rule change passed Wednesday allowing the newborns of Senate members into the chamber. Its passage without objection came despite plenty of concern, some privately aired, among senators of both parties about the threat the tiny humans pose to the Senate’s cherished decorum.

“I’m not going to object to anything like that, not in this day and age,” said Sen. Pat Roberts, R-Kan., father of three and grandfather of six. He then noted that a person can stand in the door of the cloakroom, a lounge just off the chamber, and vote. “I’ve done it,” he said. Allowing babies on the Senate floor, he said, “I don’t think is necessary.”

Sen. Orrin Hatch, the father of six, grandfather of 14 and great-grandfather of 23, said he had “no problem” with such a rules change. “But what if there are 10 babies on the floor of the Senate?” he asked.

The inspiration for the new rule is a small bundle named Maile Pearl, born April 9 to Illinois Democrat Tammy Duckworth — the only sitting senator in U.S. history to give birth. In a statement, Duckworth thanked her colleagues for “helping bring the Senate into the 21st Century by recognizing that sometimes new parents also have responsibilities at work.”

Their concerns and more were shared by Republicans and Democrats, according to interviews Wednesday.

“It is a big change,” Sen. Amy Klobuchar, D-Minn., said in a telephone interview, as leaders of both parties sought to clear the new rule without objection, or public discussion. The private reassurances to members of both parties, she said, have “been going on for weeks.”

Sen. Duckworth proposed changing the rules to allow senators with newborns — not just Duckworth, and not just women — to bring their babies onto the floor of the Senate.

Teleworking is not an option in the Senate, which requires members to vote in person. So Duckworth raised a rare question that split her colleagues more along generational lines than well-worn partisan ones. Duckworth proposed changing the rules to allow senators with newborns — not just Duckworth, and not just women — to bring their babies onto the floor of the Senate.

This, recalled Klobuchar, did not go entirely smoothly for the two months she privately took questions about the idea and its potential consequences — diaper changes, fussing and, notably, nursing.

Sen. Tom Cotton, father of two, said he has no problem with the rule change. But the Arkansas Republican acknowledged that some of his colleagues do, “so the cloakroom might be a good compromise.”

Klobuchar’s answer to that suggestion noted that Duckworth lost both legs and partial use of an arm in Iraq, and mostly gets around by wheelchair.

“Yes, you can vote from the doorway of the cloakroom, but how is she going to get to the cloakroom when it’s not wheelchair accessible?” she asked. Some senators proposed making an exception for Duckworth. But her allies said the Senate should make work easier for new parents. “We believe strongly, and she did, that it should be a permanent rules change.”

Having 10 babies on the Senate floor, as Hatch suggested, “would be a delight,” Klobuchar said.

“We could only wish we had 10 babies on the floor. That would be a delight,” retorted Klobuchar, noting that such a conflagration would probably mean more young senators had been elected in a body where the average age of members tops 60.

There was more, voiced privately, Klobuchar said — including whether Duckworth intended to change Maile’s diaper or nurse her new baby on the Senate floor.

Most senators, though, were supportive, Klobuchar said. Majority Leader Mitch McConnell, R-Ky., and Rules Committee Chairman Roy Blunt, R-Mo., both fathers, helped or did not stand in the way. McConnell did not answer a reporter’s question Wednesday about whether he had any concerns about babies on the Senate floor.

Several others were happy to voice support for the rules change, and could not resist taking a jab at their colleagues.

“Why would I object to it? We have plenty of babies on the floor,” joked Sen. Marco Rubio, R-Fla.

But there still was some confusion.

Just after the unanimous vote, Sen. Dick Durbin, D-Ill., said it would do the tradition-bound Senate some good to see “a diaper bag next to one of these brass spittoons, which sit on the floor, thank goodness, never used.”

Oklahoma Republican James Inhofe took issue with that, saying: “They don’t use diaper bags anymore. They’re disposable diapers.”

Diaper bags are generally used to carry clean diapers and other supplies when parents and babies go out. Sometimes, they hold dirty naps until they can be disposed of.