An independent group supporting Newt Gingrich has received another “substantial” contribution from billionaire casino owner Sheldon Adelson and will launch TV ads in seven states this week, a source close to the group confirmed Monday.

The source, who requested anonymity to speak freely, did not confirm the amount of the contribution but called it substantial and at least on par with two $5 million donations Adelson and his family have given previously. The group, known as Winning Our Future, will launch TV ads Tuesday in Georgia, Oklahoma, Ohio and Tennessee, with more to come Wednesday in Mississippi, Alabama and Kansas.

The cash infusion comes at a critical moment for Gingrich, whose campaign has flagged as conservative rival Rick Santorum’s has flourished. While much of the political world has been trained on Santorum’s battle to beat former Massachusetts governor Mitt Romney in Michigan and Arizona, two states that hold their primaries Tuesday, Gingrich has focused on trying to revive his fortunes by winning a series of Southern states next week, on Super Tuesday and beyond.

All four of the states where the group will begin advertising Tuesday vote on Super Tuesday; the others follow.

Judging from the independent PAC’s new ad buy, the group is following the same strategy. The ads focus on attacking Romney, portraying him as an establishment candidate and someone whom voters don’t trust or like. The ads also portray Gingrich as a true conservative and the best alternative to Romney. 

Whatever happens this Tuesday or next, Gingrich has vowed to stay in the Republican presidential nominating contest until the August convention in Tampa. In addition to trying to win a series of southern states and do well in Ohio, Gingrich is attempting to amass delegates in every state along the way, with the view that in the end, the nomination could be decided by a narrow margin of delegates. That’s why his campaign has contested the Florida primary’s “winner-take-all” rules — and why he plans to do the same after Arizona’s primary Tuesday.

A spokesman for Adelson declined to comment when reached by email in Japan, where he was traveling with the casino owner on business.