With 435 seats up for grabs every two years, House candidates typically raise more money overall than those running for the Senate, where only about one-third of the chamber's 100 seats are contested every two years.
But according to the Center for Responsive Politics, the fundraising gap is especially wide this year: Data show that House candidates have raised more than twice as much as Senate hopefuls at this point in the election cycle. The last time the discrepancy was this pronounced was in 2008, and before that, in 2002.
So far in the 2013-14 cycle, the 866 candidates for the U.S. House have raised $404 million in individual and political action committee donations. The 145 Senate candidates have raised $204 million.
Why the wider-than-usual disparity? It's still early in the campaign year, so there's no single answer. But there are lots of clues.
Here are a few possible explanations:
Sarah Bryner, CRP's research director, notes that while House fundraising is far outpacing that for the Senate, the overall money flowing to individual campaigns continues to shrink as a result of the Supreme Court's 2010 Citizens United campaign finance decision.
That ruling prohibited restrictions on political spending by corporations, associations and labor unions.
"There's now three times as much in independent expenditures than there were at this point in 2010," Bryner says. "Since Citizens United, a lot of money that would have previously gone to the party and to candidates is going to outside spending groups."