While the median net worth of members of Congress jumped 15 percent from 2004 to 2010, the net worth of the richest 10 percent of Americans remained essentially flat. For all Americans, median net worth dropped 8 percent, based on inflation-adjusted data from Moody’s Analytics.

Going back further, the median wealth of House members grew some two and a half times between 1984 and 2009 in inflation-adjusted dollars, while the wealth of the average American family has actually declined slightly in that same time period, according to data cited by The Washington Post in an article published Monday on its Web site.

With millionaire status now the norm, the rarefied air in the Capitol these days is $100 million. That lofty level appears to have been surpassed by at least 10 members, led by Representative Darrell Issa, a California Republican and former auto alarm magnate who is worth somewhere between $195 million and $700 million. (Because federal law requires lawmakers to disclose their assets only in broad dollar ranges, more precise estimates are impossible.)

Their wealth has created occasional political problems for Congress’s richest.

Mr. Issa, for instance, has faced outside scrutiny because of the overlap of his Congressional work and outside interests, including extensive investments with Wall Street firms like Merrill Lynch and Goldman Sachs, as well as land holdings in his San Diego district. In one case, he obtained some $800,000 in federal earmarks for a road-widening project running along his commercial property.

Senator John Kerry, a Massachusetts Democrat who is married to Teresa Heinz Kerry, set off an uproar last year when it was disclosed that he had docked his $7 million, 76-foot yacht not in his home state but in neighboring Rhode Island, which has no sales or use tax on pleasure boats. (Mr. Kerry, worth at least $181 million, voluntarily paid $400,000 in Massachusetts taxes after criticism.)

Representative Nancy Pelosi, the House Democratic leader, was challenged about her wealth, as much as $196 million, by a member of her own party a few weeks ago. Representative Laura Richardson, a California Democrat who is among the poorest members of Congress with as much as $464,000 in debt, attacked Ms. Pelosi at a closed-door Democratic caucus meeting for endorsing a Congressional pay freeze, according to a report in Politico that was confirmed by other members.

Ms. Richardson angrily told Ms. Pelosi that, unlike her, some members needed the raise. Members now make a base pay of $174,000 and would automatically get a cost-of-living adjustment unless they were to decide, for a third straight year, to pass it up. Sheila Krumholz, executive director of the Center for Responsive Politics, said the rising Congressional wealth fuels public doubts about whether members are more focused on their constituents’ interests or their own investment portfolios.