WASHINGTON — President Barack Obama on Tuesday hosts his first state dinner and — like the $1.4 trillion U.S. deficit — the darn thing just keeps getting bigger and bigger.

Throwing recession-era caution to the wind, Obama has invited an estimated 400 friends, political donors and — yes — even some Republican rivals to an extravagant soiree in honour of visiting Indian Prime Minister Manmohan Singh.

Months in the planning, the event has grown so large that the White House has abandoned the traditional setting for formal dinners — inside State Dining Room, which seats a mere 140 — and instead erected a massive tent on the South Lawn to accommodate the A-list crowd.

It's the second time in four years that Singh has been feted at the White House, following an 'official dinner' that Bush threw for the Indian leader in 2005.

Why India?

It's thought Obama wants to reward India for remaining a solid ally in one of the world's most volatile regions. The administration reportedly also wants to allay growing anxiety in India about U.S. efforts to strengthen ties with its regional rival, Pakistan.

"I think it's the importance of our relationship with India on a host of issues. Obviously, counterterrorism is important," White House press secretary Robert Gibbs said Monday.

"I think India, obviously, is in a very important region of the world, and I think it demonstrates the importance that that relationship has in the world."

The geopolitical reasons for the India dinner, however vital to U.S. interests, are almost an afterthought for many politicos in status-hungry Washington.

Leading up to the dinner, the biggest sport has been trying to divine who has cadged an invite to the dinner, and who has been left out in Washington's November cold.

The official list of attendees won't be released until Tuesday. But those rumoured to be on the guest list include some of Obama's biggest celebrity donors, from TV talk show queen Oprah Winfrey to Hollywood moguls Steven Spielberg and David Geffen. Hollywood agent Ari Emanuel, the brother of Obama chief of staff Rahm Emanuel, also reportedly landed an invitation.

Vice President Joe Biden and members of Obama's cabinet, including Secretary of State Hillary Clinton, will be there, as will Democratic and Republican leaders in the House of Representatives and Senate.

Invitations have also gone out to some prominent Indian-Americans. Louisiana's Republican governor Bobby Jindal, a possible GOP presidential rival in 2012, is expected to attend, as is Hollywood director M. Night Shyamalan and Sanjay Gupta, CNN's medical correspondent.

According to the Canadian embassy, Ambassador Gary Doer — a newcomer to the U.S. capital — is not attending the dinner.

"In terms of a pecking order, there is one," says Lynn Sweet, longtime White House correspondent for the Chicago Sun-Times and a columnist for Politics Daily. "The first state dinner for an administration is always going to be a big deal, no matter who the president is, no matter what the party."

Since last January's inauguration, the president and First Lady Michelle Obama have kept a busy social calendar at the White House — hosting a number of events honouring American music and culture. It has been a sharp change from the previous administration, when the running joke was about how President Bush hated Washington parties and had to be in bed by 9 p.m.

Bush hosted several state and official dinners but sometimes retired early, during the evening's entertainment.

Ahead of Obama's first dinner, there has been at least some anxiety within the White House about the optics of holding a lavish gala in the midst of a stubborn recession that has pushed the national unemployment rate above 10 per cent.

"There has been a concern that at a time when we have two wars and an economic meltdown the White House didn't want to get into too much of a celebratory mood," says Sweet. "On the other hand they wanted to maintain the traditions of American diplomatic entertaining and doing it right."

The size of Obama's party, while larger than those thrown by Bush, is not precedent setting. President Bill Clinton, during his final year in office, had 700 guests in a White House tent for another Indian prime minister, Atal Bihari Vajpayee.