Groups opposed to labeling genetically modified food outspent those in favor 5 to 1 last year when Californians voted on a labeling ballot measure. But the tables are turned in the run-up to an initiative vote in Washington state. So far, pro-labeling groups have spent more than $4 for every $1 spent by those opposed, according to an analysis by MapLight.

Contributions in support of Washington Ballot Initiative 522 (“The People’s Right to Know Genetically Engineered Food Act”) add up to nearly $4 million $3.5 million, while the opposition has raised about $950,000. The big money comes from the same interests that ponied during the California campaign, as you can see in this chart (click to embiggen).

That chart only shows the biggest contributors. Pro-labeling contributions come from a broader base; the money supporting the initiative comes from 5,698 supporters, compared to just 12 contributors in opposition.

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The relative weight of contributions, however, is likely to shift rapidly as the Washington initiative approaches its Nov. 5 moment of truth at the ballot box. Last year, the campaign against the California proposition spent $42 million in the six weeks before the vote. That proposition failed, with 6.4 million “no” votes, and 6.1 million votes in favor.

After that vote, both sides promised to fight just as vigorously in future campaigns. There are dozens of bills currently making their way through statehouses that would require the labeling of GM foods.

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Editor’s Note and Correction: This story includes a chart from MapLight showing supporters of 1-522 had given $3,869,078. The correct number is $3,489,078.13, according to a MapLight correction.

MapLight has issued this update: “A previous version of MapLight’s analysis cited the total amount raised in support of I-522 as $3,869,078, including two contributions that were disclosed by the Washington Public Disclosure Commission as having been made by ‘ORGANIC CONSUMER FUND’ when in fact they were made by ‘ORGANIC CONSUMER FUND COMMITTEE TO LABEL GMOS IN WA STATE.’ As a committee that is supporting I-522, contributions from ORGANIC CONSUMER FUND COMMITTEE TO LABEL GMOS IN WA STATE to other committees supporting I-522 should be excluded from the total amount raised in support of this measure, making the correct total $3,489,078.13.”