WASHINGTON — Big-money political contributions from the finance, real estate and insurance sectors have exploded by 700% over the last two decades, a far greater increase than campaign funds from other industries, a study said Thursday.

The study by the Sunlight Foundation, a Washington-based non-profit organization, looked at donors who gave $10,000 or more per election cycle, using 2010 dollars to control for inflation.

The researchers found that in the finance, real estate and insurance sectors, the number of those big-money donors grew from 1,091 in 1990 to 5,510 in 2010.

Those donors gave a total of $15.4 million to political candidates, parties and independent expenditure groups in 1990, but that figure ballooned to $178.2 million in 2010.

The second most prolific group of big-money contributors — lawyers and law firms — gave $59.8 million in 2010. That figure was up from $5.7 million in 1990.

Over the last two decades, the finance sector's big-money contributions were consistently bipartisan, though Republicans got slightly more money than Democrats in most years, the study's author, Lee Drutman, wrote on the Sunlight Foundation's website.

Drutman concluded that although it is difficult to measure the influence of big-money contributions on politicians, it stands to reason that the money has at least some impact.

"At the very least, candidates and party leaders will be spending more time with these financial sector donors than anybody else, hearing them out sympathetically on regulation, taxation, and other issues of concern, again and again," Drutman wrote. "At the aggregate level, it's hard to imagine this not having some impact."

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