Outside spending in the Massachusetts special election has topped $1.25 million, with most of the cash going to support Rep. Edward MarkeyEdward (Ed) John MarkeyDemocrats search for 51st net neutrality vote Overnight Regulation: Dems claim 50 votes in Senate to block net neutrality repeal | Consumer bureau takes first step to revising payday lending rule | Trump wants to loosen rules on bank loans | Pentagon, FDA to speed up military drug approvals Dems say they have 50 votes in Senate to overrule net neutrality repeal MORE's (D-Mass.) bid for the Democratic nomination.

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An analysis of Federal Election Commission filings reveals that nearly $970,000 has been spent by outside groups supporting Markey, while one group, affiliated with the International Association of Firefighters, has spent $85,000 to support Markey's Democratic primary rival, Rep. Stephen Lynch (D-Mass.).

The $1.25 million figure was first reported by the Associated Press.

Two groups — NARAL Pro-Choice America and NextGen Committee, a super PAC backed by billionaire Tom Steyer — have spent more than $208,000 opposing Lynch.

The League of Conservation Voters, which has endorsed Markey, has spent more than $556,000 so far to help elect him to the Senate seat vacated by Secretary of State John KerryJohn Forbes KerryFeehery: Oprah Dem presidential bid unlikely Dem hopefuls flock to Iowa Change in Iran will only come from its people — not the United States MORE (D). The group has pledged to spend at least $650,000 to support him.

No outside groups have yet spent for any of the three Republican candidates in the race, though one Tea Party group is planning on launching radio and television ads for Mike Sullivan, a former George W. Bush official who is considered the frontrunner in the GOP primary.

The outside spending comes even as both Markey and Lynch have signed a pledge to keep such money out of the race. The "Peoples' Pledge," which originated in the race between Sen. Elizabeth WarrenElizabeth Ann WarrenWarren: Trump is a 'racist bully' Poll: Oprah would outperform Warren, Harris against Trump in California Democrats continue to dismiss positive impacts of tax reform MORE (D) and former Sen. Scott Brown (R), bars outside groups from launching ads on television, radio or online in support of -- or opposition to --- a candidate in the race.

But a handful of groups have found loopholes in the pledge, and continue to pump funds into the race — efforts that, due to the shortened timeline and low turnout expected for a special election, could notably impact the results.

Canvassing, sending informational mailers to a group's members and polling are all beyond the scope of the pledge.

And at least one group, Steyer's NextGen Committee, has flouted the pledge, launching an online petition drive highlighting Lynch's support for the Keystone XL pipeline. Both candidates say that drive violates the pledge. Though Markey and Lynch have expressly asked him to stay out of the race, Steyer has refused to pull back his efforts.

The candidates have just three weeks until the April 30 primary, and the Democratic nominee is expected to win the seat in the general election.