That's the first time the median has exceeded $1 million, the center found in a survey of congressional and candidate financial disclosures. There are 268 current members who had a net worth of $1 million or more, up from 257 members, or 48 percent, a year earlier.

The milestone comes as Congress is having difficulty approving benefits for people who have less, such as extending expanded unemployment benefits, funding for food stamps and increasing the minimum wage.

"Despite the fact that polls show how dissatisfied Americans are with Congress overall, there's been no change in our appetite to elect affluent politicians to represent our concerns in Washington," Sheila Krumholz, executive director of the center, said in a statement on the group's website.

$174,000 salary

Senators and representatives earn a base annual salary of $174,000, not counting benefits, though lawmakers in leadership positions can earn more. Permissible outside income is capped at just more than $27,000, according to the Congressional Research Service, though members can claim a tax deduction of up to $3,000 to offset living expenses while in Washington.

Lawmakers are also given taxpayer funds to run their offices at the Capitol and in their home districts, and to cover official expenses.

Precise wealth figures are hard to determine through Congress's financial disclosures, which report holdings in broad ranges that become less precise as the amounts rise. At the top end that can mean reports are off by tens or hundreds of millions of dollars.

Lawmaker wealth varies widely, from Representative Darrell Issa, with a fortune the center estimated at $464 million built on car alarms, to Representative David Valdado, who reported $12.1 million in net liabilities related to outstanding debt on loans for his family's dairy farm.

Student loans

The disparity means lawmakers often don't have to deal with some of the same financial issues as their constituents. Lawmakers, for instance, clashed at least twice in the past two years over whether to allow government-backed student loan rates to double.

Student lending is now the second-biggest category of consumer lending in the U.S., surpassing credit cards and trailing only mortgages. A Bloomberg review of financial disclosures during 2012 found that very few lawmakers reported student-loan debt, including only one member of leadership, Republican Representative Cathy McMorris Rodgers.

Krumholz said it's "undeniable" that to run for office in the U.S. "candidates need access to wealth to run financially viable campaigns, and the most successful fundraisers are politicians who swim in those circles to begin with."