Despite candidates' signatures on the so-called "People's Pledge"  to keep outside big money groups out of a special Massachusetts Senate election, the Democratic primary has attracted nearly $1.3 million in outside spending so far.

All but seven percent of that money has been in favor of frontrunner Ed Markey — either in support of the veteran Democratic congressman or in opposition to his rival (and House colleague) Stephen Lynch. Lynch has only seen help from one group — the firefighters union, according to reports filed with the Federal Election Commission.

The special election is to replace former Sen. John Kerry, who became President Barack Obama's secretary of state earlier this year. 

The big spending so far has been on voter mobilization, mainly from various arms of the League of Conservation Voters and the influential Service Employees International Union. Technically, that money doesn't violate the pledge, in which Markey and Lynch swore off advertising and direct mail.

But some of the outside spending does. Despite Markey attempting to shoo him away, California billionaire Tom Steyer, who opposes the Keystone Pipeline, has dropped $145,580 in ads through his new NextGen super PAC, including a sarcastic web video (seen below) with actors playing lobbyists. They thank Lynch for his support and compare the Democrat to oil patch Republicans such as former President George W. Bush and the Koch brothers. In addition, Steyer funded a snarky aerial banner that claimed Lynch was urging Bostonians to root for a Canadian hockey team against the Boston Bruins because he likes "Canadian dirty oil."

Markey's campaign has said it would pay half the cost of the online ads to a charity of Lynch's choice, in compliance with the pledge.

Another anti-Keystone group, 350.org, is mobilizing college students across the Bay State to vote for Markey, the Republican newspaper reported Thursday.

The primary takes place on April 30 and the general election is set for June 25.