The senator led the group back out into the hallway, to walk the 13 paces from Room SR-131 to Room SR-132. As TV cameras filmed, he opened the door, and held it while the group filed in.
Isakson, who has expressed openness in the past to increased background checks, is part of a small bipartisan group of senators who could control the fate and the content of a potential gun bill. The group also includes Manchin and Toomey.
Manchin and Toomey have discussed expanding background checks to all commercial sales - whether at gun shows, via the Internet, or in any circumstance that involved paid advertising, according to people familiar with their conversations. That would be more stringent than the current rule, which requires checks only when purchases are made through a licensed dealer.
But background checks would not be required for many sales between private individuals.
That would stop short of a proposal offered by Sen. Charles Schumer, D-N.Y., and backed by the White House that would require background checks for nearly every kind of sale.
Toomey has been under pressure to make progress on firearm-related issues. Pennsylvania's other senator, Robert Casey Jr., a Democrat, broke with the NRA after the Newtown shootings and political organizing around gun control has increased lately in Pennsylvania, in part the result of funding from Mayors Against Illegal Guns, an organization funded by New York Mayor Michael Bloomberg, a political independent.
But there is also strong pressure from the other side. In Toomey's office on Tuesday, a receptionist assured one unhappy caller that the senator is a strong supporter of the Second Amendment.
There was a pause on her end. The caller was asking about the one area in which Toomey's position is unclear.
"The senator himself has not released a statement on background checks yet," she said.
The next step is the vote planned for Thursday. It's necessary because of a filibuster threat led by the Senate's conservative wing, which wants to block the Senate from debating a gun-control bill.
For now, it looks as though that effort will fail.
Some Republicans said they would vote with Democrats to end any filibuster and let the debate begin. Democrats need their votes because they cannot count on the votes of all 55 of their senators.
If Reid can get 60 votes, the debate will begin. And then things will get complicated.
Senators from both parties are likely to introduce numerous amendments. One might establish an online portal for background checks, and provide more federal funding for mental health programs assisting veterans of the wars in Iraq and Afghanistan. There also probably will be amendments backed by the NRA, designed to make the bill less onerous for gun owners and gun buyers.
Any bill would need only a majority of votes to pass. After that, it would go to the GOP-led House, where another long process could begin.