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.

[IMGCAP(1)]Now, as the first Senator since John F. Kennedy to be elected to the White House, Obama is using the Senate’s 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 Obama’s 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 Obama’s “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, Obama’s Oval Office open-door policy offers Senators the sense that they are being taken as seriously by him as they sometimes take themselves.

“Some of it is about showing respect for the role they play in the process,— one White House official said.

According to participants, Obama doesn’t jawbone, doesn’t twist arms and doesn’t give the hard sell. He makes his positions clear but doesn’t force the issue.

“He wants to know how you get there from here,— Wyden said. “I think he shows considerable tact in this. He lets you know where he stands, but you never feel there’s pushiness.—

Instead, Senators who have sat down with the president describe a discussion, sometimes well into the weeds of policy, in which the president spends more time probing Senators’ views and reasoning than he does expressing his own.

“He takes complicated information and synthesizes it as well as anybody I’ve ever seen,— Wyden said.

Obama often seems to be looking for ways to address a Senator’s concerns without compromising his own views.

“It gives an idea of where I may be flexible and where he may be flexible,— Snowe said. “So I think he’s testing.—

Nelson described Obama as “very willing— to listen to ideas. “He asked questions. That’s where the dialogue begins,— Nelson said.

No Senators interviewed who had met privately with Obama acknowledged directly altering a viewpoint based on the meetings. But all said the sessions with the president have a subtle effect.

“It helps me to understand his viewpoint and where he’s coming from,— Snowe said. “It’s always helpful to factor that in.—

Snowe has been a particular target for Obama as the Republican most likely to back his health care initiative.

“The president is influential, and I’m inclined to support him,— Landrieu said. “But I’m determined to have the voice of small business and moderates heard in the administration.—

Landrieu said she pressed Obama on holding down health care reform costs and ensuring the health insurance exchanges are “made robust for small businesses.—

Obama’s approach contrasts with that of former President George W. Bush, an ex-governor and confirmed Washington, D.C., outsider who generally met with lawmakers in small groups or called them on the phone, according to a former senior Bush aide. President Bill Clinton also worked the phones, frequently well into the night. Obama uses all those techniques, too.

But perhaps none is as effective as a private meeting with the president in the world’s most famous office.