Ever so quietly, Microsoft (NASDAQ: MSFT) has retained big PR firm Burson-Marsteller and has been trying to convince internet companies and regulators that the Google (NASDAQ: GOOG) plan to buy DoubleClick will hurt competition. Given Microsoft's past relationship with the government and other software companies, the move has a touch of irony.

According to The Wall Street Journal "the campaign is one piece of a broader effort by Microsoft to rally opposition to the acquisition..." The world's largest software firm has also approached companies including Time Warner (NYSE: TWX) and AT&T (NYSE: T) to enlist support. Burson has contacted several companies without saying that Microsoft is its client in the matter.

The move may show how desperate Microsoft is to keep Doubleclick, a huge force in serving display advertising for thousand of clients onto internet websites, away from Google. The world's No.1 search company could use its targeting software to help place display ads more efficiently. That would give Google a very significant business in the display market to sit along side it dominant position in providing search base text ads.

Microsoft's MSN portal and Live search products have lagged behind Google and Yahoo! (NASDAQ:YHOO) in both search market share and overall internet audience. If Google increases its influence in the internet ad business, Microsoft may have permanently lost its chance to catch up.

Douglas A. McIntyre is a partner at 24/7 Wall St.