How things have changed since Congress banned soft money.

Flash back to Los Angeles in 2000. One of the best parties at the Democratic convention in 2000 was a blockbuster concert featuring Sheryl Crow at the Sunset Room nightclub — an ultra-chic Hollywood hotspot known for frequent sightings of P. Diddy, Macy Gray and Dennis Miller.

The bash, thrown by the Democratic Senatorial Campaign Committee, was open to hundreds of wealthy Democrats who contributed $50,000 to $100,000 to help elect Democratic candidates to the Senate.

Tonight, the DSCC holds the encore to its splashy Los Angeles party at Boston nightclub Felt. This time around, the entertainment is a little less flashy. The headliner this year is Sen. Jon Corzine, the balding 57-year-old Senator from New Jersey who chairs the DSCC.

In the nearly two years since soft money was outlawed, the DSCC and other national political parties have learned how to replace checks of $50,000, $100,000 or more with thousands of smaller, hard-money contributions of $100, $1,000 and $2,000.

And political candidates have reluctantly come to accept that they will no longer be able to rely on their political parties to dip into soft-money accounts to fund million-dollar ad blitzes in the days before the election.

But this week, a lesser-known consequence of the new soft-money law will take center stage.

Without soft money, the political parties can no longer afford to throw lavish parties at their quadrennial political conventions.

“Electing candidates is more important than throwing parties now,” Corzine said. “Spending hard money on parties is not a good idea.”

That means no Bruce. No Britney. Not even Justin Timberlake.

Whereas donors to the Los Angeles convention could expect to see Barbra Streisand, Cher, Michael Bolton, Toni Braxton, Shirley MacLaine, Diana Ross, Babyface, Whoopi Goldberg, Paul Anka and dozens of other A-list stars, this week’s top stars are decidedly lower budget: Los Lobos, the Black Eyed Peas and the Red Hot Chili Peppers.

“It’s no Super Bowl halftime show,” said Darrell Henry, a lobbyist with the American Gas Association who is spending $700,000 on a half-dozen parties at this week’s Democratic convention and at the GOP convention in New York next month.

“Times are different now,” added Gloria Dittus, a Democrat who has been partying at the political conventions since the 1970s. “The parties still have fun talent — but they have talent that is affordable and doesn’t require huge production capability.”

Even David DiMartino, who served as the chief spokesman for the DSCC four years ago, conceded that the party scene in Los Angeles four years ago will surpass this week’s events.

“The new McCain-Feingold law has really cut down on the ability of the party committees to host the kinds of events that they did in L.A.,” DiMartino said.

In addition to lowering the talent profile, the campaign-finance law has crimped the number of confabs that the political parties will throw this week.

In 2000, the DSCC alone spent nearly $4 million to throw 23 cocktail receptions, dinners, lunches and late-night parties during the Los Angeles convention. This week, the DSCC is sponsoring just a half-dozen events.

The DSCC’s top event — tonight’s late-night party at the Felt nightclub — will be co-sponsored with its House counterpart, the Democratic Congressional Campaign Committee.

“There certainly has been a change in the number and scale of events,” said Monica Notzen, a Republican fundraiser. “Campaign-finance reform changed a lot of things for everyone.”

To be sure, there will be plenty of private parties this week — more than 200 at last count. And with the political parties largely vacating the party scene, corporations and other outside groups have stepped in to fill the party vacuum.

Now that corporations cannot curry favor with lawmakers by writing soft-money checks to the political parties, they have “sought out other ways to show the political parties that they’re players,” according to a report by Meredith O’Brien of the Center for Public Integrity. “One solution: Lavish parties at the presidential nominating conventions.”

But the campaign finance law also has made it more difficult for corporations to throw parties in honor of a lawmaker, because the law prohibits lawmakers from helping plan the event and rounding up donations to pay for the parties.

“Campaign-finance reform took the party committees completely out of the formula, which means that the parties have to be private parties or charity events,” said Tim Jenkins, a lobbyist who is organizing a 1,000-person bash in honor of retiring Sen. John Breaux (D-La.). “Before, donors would give a big chunk of money to the DNC, and the DNC would host the majority of the parties.”

Take Breaux’s bash. During the Los Angeles convention in 2000, Breaux’s “Mardi Gras Goes Hollywood” was a highlight of the week. The lavish party was held at the same Paramount Studios lot used for “Ally McBeal” and “NYPD Blue” and featured spicy Cajun cuisine, a guest list of 1,500 people and performances by swing band Big Bad Voodoo Daddy, the Zydeco Twisters and Rockin’ Dopsie Jr.

Breaux led the party’s parade in an orange nylon outfit with festive Mardi Gras beads in one hand and a yellow parasol in the other.

Breaux paid for the party by asking AT&T, Lockheed Martin Corp., Bristol-Myers Squibb and more than two dozen other companies to chip in $10,000 to $50,000 a piece.

This year, Breaux is prohibited from planning the party or asking companies to pay for it.

“With the new law, I can’t do it,” he said.

To put on this year’s bash, Breaux has relied on two old friends — lobbyist Jenkins and Wayne Smith, a former chief of staff — to organize the party and recruit companies to pay for the event.

Breaux “has been completely out of the loop on this one,” Jenkins said. “He knows that there is a party being thrown in his honor. He knows where it is and when it is. And that’s basically all that he knows.”

Together, Jenkins and Smith persuaded nearly 30 companies to contribute $10,000 to $30,000 to underwrite the party, which will cost more than $200,000, Jenkins said.

Companies that agreed to co-sponsor the Breaux party will have their names displayed at the event and on its invitation.

“We did not have trouble, but it’s not like they flocked to us,” Jenkins said.

The 1,000-person, Caribbean-themed party — which the retiring Louisiana Democrat has tongue-trippingly dubbed “Breaux’s Beer Beachballs Bikini Bingo Bistro Bash on the Beach in Boston” — will be held tonight at the New England Aquarium. Reggae star Ziggy Marley and a chorus of steel drums will provide musical entertainment.

Breaux isn’t concerned about how the rules change could affect his bash.

“My party in L.A. was fun, but this is going to be even better,” Breaux said. “I’m going to have one hell of a great party.”