Four years ago at the Democratic National Convention in Boston, about 700 lucky guests gathered at the city’s Museum of Fine Arts for a lavish party honoring Rep. Steny Hoyer (Md.) and Sen. Harry Reid (Nev.). Guests were serenaded by Natalie Merchant as they mingled among priceless 17th-century paintings. Nearly two dozen corporate sponsors including the Altria Group, Fannie Mae and FedEx lined up to pick up the tab.

This week will offer a very different picture. Neither Hoyer nor Reid, now both Majority Leaders in their respective chambers, is headlining a nighttime bash at the Democratic convention in Denver. With a few exceptions, Congressional leaders in both parties are following suit.

As thousands of party faithful prepare to descend on Denver and Minneapolis-St. Paul for the first conventions since lawmakers tightened ethics rules, both events will be notable for what they lack: the succession of no-expense-spared, corporate-sponsored celebrations of leaders, which had come to define the social agenda at recent conventions.

That’s not to say there will be a shortage of partying in either city. In Denver, Kanye West will be performing at an event co-sponsored by the ONE Campaign and the Recording Industry Association of America, the Distilled Spirits Council is throwing a “Spirits of Denver” party, and Google is teaming up with Vanity Fair for a bash. All told, there are more than 400 events set for both conventions, according to a tally by the Sunlight Foundation.

But outside the convention halls, Congressional leaders are mostly hugging the sidelines — the result of ethics rules adopted last year that forbid lawmakers from attending corporate-sponsored events that honor them specifically.

Among the top six Senate leaders, only two are headlining convention parties this year, and they are doing so on their own dime. Reid, Minority Leader Mitch McConnell (R-Ky.), Democratic Conference Vice Chairman Charles Schumer (N.Y.) and Republican Conference Chairman Lamar Alexander (Tenn.) all have opted out of hosting or serving as the star at any parties.

Similarly on the House side, of the top eight leaders, only Speaker Nancy Pelosi (D-Calif.) and Democratic Caucus Chairman Rahm Emanuel (Ill.) are headlining major events. Hoyer, Majority Whip James Clyburn (D-S.C.), Minority Leader John Boehner (R-Ohio), Minority Whip Roy Blunt (R-Mo.), Chief Deputy Minority Whip Eric Cantor (R-Va.) and Republican Conference Chairman Adam Putnam (Fla.) are all taking back seats on the party circuit.

The exceptions are Senate Majority Whip Dick Durbin (D-Ill.), who is co-hosting an event tonight with fellow Illinoisan Emanuel, and Senate Minority Whip Jon Kyl (Ariz.), who is throwing an afternoon reception during the second day of the GOP nominating event that begins next week in St. Paul.

Kyl, Durbin and Emanuel have a special stake in this year’s conventions. They are home-state allies to their parties’ respective nominees, Sens. John McCain (R-Ariz.) and Barack Obama (D-Ill.), and have served as top surrogates for the two presidential hopefuls.

Durbin spokesman Joe Shoemaker said the Durbin/Emanuel party, officially “Chicago Night in Denver,” is a reflection of his boss’s close relationship with Obama and a desire to get the Illinois delegation together to revel in the candidacy of one of their own. He added that Durbin and Emanuel “kept an eye on the rules and made sure we paid attention to that” when planning the event. The two lawmakers, featured side by side as the Blues Brothers in a cartoon on the invite, are splitting the cost of the event out of their respective campaign committees — accounts with lower contribution limits and tighter controls than their leadership political action committees.

“This party was less about Sen. Durbin and Congressman Emanuel being leaders in Congress,” Shoemaker explained. “It was more about them being prominent Illinoisans who are friends of Barack Obama’s and want to celebrate the fact that a fellow Illinoisan will be nominated by his party to be president.”

Pelosi is hosting three events throughout the week. She is the featured guest at a “hospitality suite” in the Grand Hyatt late Sunday afternoon. Tonight, she is the guest of honor at the “Salute to Speaker of the House Nancy Pelosi,” a bash at the Denver Center for the Performing Arts featuring performances by Tony Bennett and John Legend. And she is hosting a tea for female Members of Congress on Wednesday afternoon at the Pinnacle Club atop the Grand Hyatt. The Democratic Congressional Campaign Committee is picking up the tab for all three events, which are designed as thank-yous to donors. “A lot of DCCC supporters will be in Denver to share in the excitement of the convention, and it’s an opportunity to thank them for their support,” DCCC spokeswoman Jennifer Crider said.

Hoyer and Clyburn are hosting smaller-scale daytime events this week. Hoyer is throwing a candidate luncheon this afternoon, paid for by his leadership PAC. And Clyburn is teaming up with Rep. John Spratt (D-S.C.) to put out a lunch spread Wednesday for the South Carolina delegation. Clyburn spokeswoman Kristie Greco said he is paying for the event with campaign funds.

For the government watchdogs who pushed to stop lobbyists from feting lawmakers at conventions, the calendar of events indicates that the reforms are doing the trick. “The lavish parties and receptions that were funded by lobbyists to honor a Member or a committee chairman or leadership are not going to occur at these conventions,” Democracy 21 President Fred Wertheimer said. “It looks like to the extent that leaders are having events, they’re funding them through campaign committees or other types of campaign funding.”

The new ethics rules are the primary reason for the leaders’ approach to partying in 2008, but add the fact that both presidential nominees have thumbed their noses at lobbyists, typically the bankrollers of the convention parties. Also, in the case of the Senate Republican leaders, many of them are more concerned about their re-election campaigns than putting together a costly and time-consuming convention event.

“It’s just not worth the trouble, that’s the general feeling,” a senior Senate Republican aide said. “It’s too complicated. People are thinking about other things than conventions, and the amount of energy one would have to put in to figure out the system alone is prohibitive.”

Reid spokesman Jim Manley agreed, saying, “Members just decided it wasn’t worth the hassle. Besides, it was never really Sen. Reid’s idea of fun anyways.”

Manley said there’s a growing feeling among Democratic leaders that the conventions were becoming too focused on “glitter and glitz” and moving away from the formal selection of a presidential candidate. “Who is invited to what party was dominating the convention. More and more people are beginning to move away from that.”

While there will be plenty of celebrations in Denver and Minneapolis, they will have a different feel. Not only will fewer party leaders be hosting events, but the rank-and-file lawmakers will be headlining fewer parties as well.

“A lot of people are having things, but not for Members and not sponsoring Members,” said Hoyer, whose party in 2004 with Reid was a hot ticket. “Some Members are having fundraisers, but they aren’t Member-specific.”

Hoyer said the leaders’ new approach to the convention party scene began when Democrats won control of Congress in 2006, bringing with them new ethics rules to keep lobbyist and interest groups at arms length. Hoyer said he thought “it’s a good thing to have happened” because the conventions should be about the candidate, his or her agenda for the country and a coming together of the party around their standard-bearer.

Asked why he decided to skip playing host this year, Hoyer said: “I didn’t think it was necessary. I will see a lot of people at other places. Of the four days, I am going to 20, 22, 25 events — that’s pretty busy. I am going to see a lot of people. It’s not necessary to do a 21st event for them to go to.”