The music was rock'n'roll for Republicans - anthems designed for people who occasionally wear jeans but tend to iron careful creases into them when they do.
There was a little vintage Springsteen, a touch of Steve Miller and even Sweet Caroline by Neil Diamond. At that point, the DJ instructed the crowd to sway back and forwards, as though he was worried that a crowd of conservatives would be inclined to stand to attention, even at a party.
But if the evening had an anthem, it was surely Don't Stop Believing, which pounded out through the sound system as it became clear that the race for Barack Obama's old seat in the Senate was a lot tighter than the GOP faithful would have liked.
When they began to gather in the ballroom of a hotel in the prosperous Chicago suburb of Wheeling, all was optimism.
These were not Tea Party Republicans with strident banners about the constitution and warnings about the urgency of the need to restore American liberty.
I spotted one man in a Revolutionary War-era tri-corn hat and one woman in a Stars and Stripes top, but broadly speaking, these were old-fashioned, soberly-dressed mainstream conservatives quietly confident that this time around they were working with the grain of history.
A Republican year
Their candidate too was the experienced campaigner Mark Kirk, rather than an untried outsider with a past full of booby-traps, foisted on them by Tea Party activists through the Republican primary season.
True, he had had the odd embarrassing moment when he was caught apparently exaggerating the precise nature of his military service, but in a Republican year Mr Kirk was the sort of solid conservative you would expect to do well.
And of course, his opponent, Alexi Giannoulias - the Democrat charged with the heavy responsibility of keeping Mr Obama's old seat within the party fold - was known to be personally close to the president.
It was not his only problem of course - there were issues with a family-run bank too.
But in a year when the lustre has been knocked off the president's reputation, it probably helped the Republicans that the Democratic candidate was a man who had known Obama since they met playing a game of basketball at University.
Still for a long time, the hottest action in the ballroom was the long and painstaking installation of a series of clusters of red white and blue balloons around the room.
The political news trickled in as the balloons were set out.
The polls closed as a man with a long pole fitted with a rubber suction cup was deployed to recover and rescue stray balloons which had drifted up to the high ceiling.
An America run by these folks, you sensed, would be a well-run place, free from errant balloons.
As the room began to fill up, and the cash bars opened, groups of activists began to gather around the television sets, cheering every update that showed Mr Kirk leading his rival.
But it was to be a long time before it became certain that their man was going to win. Well over 90% of Illinois votes had been counted before they were confident of victory.
Once it was assured, Mr Kirk emerged to give a strong measured speech implying that bi-partisan co-operation would be available to Mr Obama - but only if he reacted to the results of the evening by moving to the right.
The activists were cheered - they heard the message they wanted on debt and deficit and they are confident they have clipped Mr Obama's wings. Plenty of them assured me they were certain he would be a one term president.
For the faithful, the message of the song Don't Stop Believing was vindicated.
For Mr Obama there was an altogether grimmer message. Chicago was the scene of his speech where he proclaimed his great presidential victory.
Who would have thought the city that gave him a night to remember only two years ago would give him a night to forget so soon afterwards?