A new conservative outside group is launching a big ad buy in Massachusetts on behalf of Republican Gabriel Gomez's special election campaign.

The group, called Americans for Progressive Action, is spending about $700,000 on ads over the next week, according to a person familiar with the buy.

A contact for the group has yet to confirm the ad buy

The spending lends Gomez some key late assistance in his uphill battle against Rep. Ed Markey (D). Republicans are optimistic that they can pull another upset in the Bay State three years after Scott Brown shocked the world with his special election win.

Little is known about Americans for Progressive Action. The group filed with the Federal Election Commission just last week and doesn't appear to have a website. It's treasurer, Nancy Watkins, has been associated with many lesser-known outside group in recent years.

Gomez has also gotten some air cover from the state party, which may have gotten money from the national GOP. But the effort to boost his candidacy so far hasn't reached the level of the pro-Brown effort in 2010.

National Democrats are running ads on Markey's behalf, and a big Democratic super PAC added to its buy earlier Wednesday.

President Obama also lent Markey a hand Wednesday, and Bill Clinton will stop by this weekend.