Obama campaign buys more time

There is a gauge for measuring election nights - I call it the decibel guide.

If the candidate is doing well, the celebration party is so rowdy you can't hear a damn thing. If the candidate is doing less well than expected, then a tired reporter can file her story in peace and quiet.

Tonight there were moments of both at the Obama headquarters in Chicago - this was, after all, a confusing race.

The crowd went crazy when states were called for the Illinois senator, but there were long periods of calm in between as states went to Hillary Clinton.

REPORTS FROM THE CAMPS

McCain's road ahead

Subdued mood at Romney HQ

Excitement in Clinton camp

They would never say it, but the Obama campaign was looking at the most recent polls and in their most secret hearts they were hoping to deliver a decisive blow to the senator from New York.

The campaign went into these primaries hoping the Obama momentum could blow across the nation the way the wind blows through this city.

Still a split

That did not happen, so the spinners were out working overtime putting a positive gloss on the evening.

It's all about the delegates, they told me. Massachusetts and New Jersey were never part of our strategy, they added. We always expected her to win tonight, they insisted.

All true. Well... -ish.

It gets your head turning, being surrounded by so many ardent campaign workers. After a bit you can't tell what's spin and what's real - and sometimes I wonder whether the staffers can either.

As the Obama team sent out high profile surrogates to mingle with us lowly journalists, they told a tale of victory and expectations exceeded.

As for the supporters, they were happy enough. They cheered another cracking stump speech by their man.

His rhetoric is partly what they love him for, and as he hit the high notes tonight, the crowd went wild with chants of "Yes We Can!" A nifty slogan that one - and, no coincidence perhaps, so easily translated into Spanish.

The night ended as it started - a split.

Obama left this hall knowing he has bought himself time, not a win, but also knowing that in this game of delegate roulette, he has enough money to carry on playing.

Katty Kay is the Washington correspondent for BBC World News America, airing at 0000 GMT (1900 ET / 1600 PT) every weekday.