As a Senator, President Barack Obama was introduced to the collegial ways of the institution, where friends can be like brothers and sisters, and even political enemies will sit down privately to hash out differences.
Now, as the first Senator since John F. Kennedy to be elected to the White House, Obama is using the Senates tradition of personal relationships and private stroking of egos to advance his agenda.
Obama has developed his own specialized lobbying technique, meeting regularly in one-on-one sessions with Senators to go through an issue and try to win their support.
But unlike in the Senate, where circumspection is key, the Senators who troop to the White House are often filmed coming in and out and are besieged by reporters after their meeting.
In fact, according to one knowledgeable source, some Senators have been rankled and surprised that their meetings are announced by the White House beforehand.
Nevertheless, with Obamas commitment to transparency, the White House continues to announce many of the meetings on the daily schedule circulated to reporters.
The meetings are sociable, but not social.
Obama is opening up the ultimate hideaway the Oval Office to his former colleagues because he wants their backing. Many of those who have gotten the invite are moderates who hold the key to the fate of health care reform in the Senate.
Meanwhile, a few who were close to Obama in the Senate including Republican Dick Lugar (Ind.) have not met privately with the president. White House officials could not remember Obamas best friend in the Senate, Democrat Dick Durbin (Ill.), coming by for a private chat, though the two are in touch by phone.
He has used the conversations mainly to lobby for his health care initiative, though he has also sat down with various committee chairmen to discuss other issues.
Frequently, the meetings include just Obama and his guest, though at times White House aides such as Chief of Staff Rahm Emanuel, health czar Nancy-Ann DeParle, or Legislative Affairs Director Phil Schiliro have been in the room.
The sessions have included key health care swing votes such as Sens. Kent Conrad (D-N.D.), Ben Nelson (D-Neb.), Mary Landrieu (D-La.), Max Baucus (D-Mont.), Olympia Snowe (R-Maine), Blanche Lincoln (D-Ark.) and Evan Bayh (D-Ind.), who stopped in for a chat just last Thursday.
A few sessions have been with Republicans, including Snowe, and Sens. Tom Coburn (Okla.) and Lindsey Graham (S.C.).
Graham met Thursday with Obama to talk about Afghanistan.
Among the others admitted privately to the inner sanctum are Sens. Debbie Stabenow (D-Mich.), Patrick Leahy (D-Vt.), Ron Wyden (D-Ore.), Jay Rockefeller (D-W.Va.) and John Kerry (D-Mass), who offered the president a download last month on his discussions with Afghanistan President Hamid Karzai.
With Senators famously prickly when it comes to their prerogatives, Obamas Oval Office open-door policy offers Senators the sense that they are being taken as seriously by him as they sometimes take themselves.