The planned $750M acquisition of AdMob by Google announced earlier this year is stuck in limbo as two consumer groups today began to lobby the FTC to block the purchase, claiming it is anti-competitive and raises privacy concerns.

In addition to the groups lobbying the Federal Trade Commission, the organization also sought more information about the deal last week, according to a Wednesday post on Google’s blog. This ongoing investigation into the deal by the FTC has the potential to permanently halt the largest acquisition in mobile advertising and Google’s history, but may just be a necessary pause before allowing Google to dominate the sector.

With $22 billion in expected revenue this year, the deal, which could help Google become a monopoly in the mobile advertising space in time, needs to be carefully scrutinized by the FTC and anti-trust groups, however, it may still pass. This greatly concerns many involved in the space.

“The mobile sector is the next frontier of the digital revolution. Without vigorous competition and strong privacy guarantees this vital and growing segment of the online economy will be stifled,” wrote John M. Simpson, consumer advocate at Consumer Watchdog and CDD Executive Director Jeffery A. Chester, in a statement.

In a joint letter to the FTC, Consumer Watchdog and the Center for Digital Democracy (CDD) said Google is “simply buying its way to dominance in the mobile advertising market, diminishing competition to the detriment of consumers.”

“Consumers will face higher prices, less innovation and fewer choices,” said Chester. “The FTC should conduct the appropriate investigation, block the proposed Google/AdMob deal, and also address the privacy issues.”