As outside groups begin to mobilize in the Massachusetts Senate race, the animosity between the Republican Gabriel Gomez and his Democratic opponent, Rep. Ed MarkeyEd MarkeyACLU sues DHS for records on purchased cell phone data to track immigrants DHS watchdog to probe agency's tracking of Americans' phone data without a warrant Manchin: Ocasio-Cortez 'more active on Twitter than anything else' MORE, is reaching a fevered pitch.  


The increasingly personal nature of the attacks could soon be amplified as outside money begins to pour into the race before the June 25 election. 

Reacting to negative television ads on Thursday, Gomez angrily referred to Markey as “pond scum,” elevating a line of attack from his campaign that also branded the Democratic congressman as “Dirty Ed Markey.”

Gomez’s campaign downplayed the "pond scum" comment and told The Hill the remarks were unscripted. An aide noted that the candidate is a “plainspoken Navy SEAL.”

“We're surprised at the controversy,” a Gomez aide said. “Pond scum has a higher approval rating than Congress.”

Gomez made the remarks while criticizing recent ads run by his opponent: One highlighted Gomez’s opposition to restrictions on high-capacity ammunition magazines while invoking the Newtown school shootings; the other showed a picture of Gomez alongside one of Osama bin Laden.

National Democrats were quick to jump on Gomez’s remarks by blasting them out to reporters. They claimed the remark is a sign that Gomez is losing control of his campaign.

Markey’s campaign said Gomez reached a “new low.”

Spencer Kimball, a political consultant who did some work for Gomez’s GOP primary opponent Dan Winslow, said Gomez’s remarks were a rookie mistake and will likely feed the Democrats’ narrative.

“It is certainly an undisciplined move,” said Kimball, who is also a political communication professor at Emerson College. “This is the U.S. Senate. This is not a state race, a local race. This is about as big as it gets, so you’ve got to make sure that you control your message and stay on message.”

Both candidates have recently lobbed attacks at one another over recently released tax returns and national security issues. Markey continues to lead in polls by about 10 percent, according to the Real Clear Politics average.

The personal invective comes just as billionaire climate activist Tom Steyer’s super-PAC announced it would begin to spend money in the race to support Markey. Steyer’s group, NextGen, spent $650,000 in the Democratic primary to attack Rep. Stephen Lynch (D-Mass.).

According to a strategy memo released by the group, it aims to be a “politically disruptive force” between now and Election Day and will attempt to brand Gomez as “Mitt Romney Lite.”

During the primary, the group attempted to work within the confines of a pledge — dubbed the People's Pledge — that was signed by both Democratic candidates and would have triggered financial penalties when outside groups spent money on campaign ads. No agreement has been made between Markey and Gomez in the general election.

NextGen will focus again on field organization and “Guerrilla marketing” but also vowed to spend money on “paid media,” specifically online tactics.

“We saw this in the [Scott] Brown [Sen. Elizabeth] Warren race,” Kimball said, referring to last fall's Senate race in the state. 

“When the candidates run the ads, they go only so far with your face and your name behind it. Now without any protection from those outside groups, you are going to see real hard-hitting ads, unless the candidates themselves call them off.”

According to reports, the National Republican Senatorial Committee is sending at least four staffers to the state to help with strategy and fundraising on Gomez’s campaign. 

However, two of the highest spending super-PACs, Majority PAC on the left and American Crossroads on the right, have remained noncommittal about their decision to enter the race.

Ty Matsdorf, communications director for Majority PAC, told The Hill no decision has yet been made about spending money in the race. But NextGen vowed to help support the group if it does enter.

Last election cycle, Majority PAC spent $300,000 supporting Elizabeth WarrenElizabeth WarrenSchwarzenegger says he would 'absolutely' help Biden administration Disney chair says he would consider job in Biden administration if asked Despite veto threat, Congress presses ahead on defense bill MORE in the state.

American Crossroads said earlier last week it was still in the decision phase.

This story was updated on May 26 at 5:07 p.m.