Google is under siege in Washington like never before and it says an “anti-Google industrial complex” is to blame. In an interview recently, a Google spokesman argued that a cabal of antitrust lawyers, lobbyists and public relations firms is conspiring against the Internet search giant. The mastermind? Google says it’s Microsoft.

In the 1990s, Microsoft was the tech industry wunderkind that got too big for its britches and Google CEO Eric Schmidt, then an executive at Sun Microsystems and later Novell, helped knock the software titan down a peg by providing evidence in the government’s antitrust case against it. The constraints imposed on Microsoft in that case helped clear the way for Google’s rise to rule the Web.

Now as Google spreads its tentacles into everything from mobile phones to digital online libraries to green energy, some of Microsoft’s allies are saying it’s time for the search giant to get its comeuppance. “There is so much conduct that should be investigated,” said Pamela Jones Harbour, a former Federal Trade Commission member, who opposed Google’s merger with online advertising firm DoubleClick in 2007. Harbour, now an attorney specializing in competition issues, consults for Microsoft on competition and policy issues, and she says Google now has a monopoly.

But there are also increasing calls from some Silicon Valley competitors and Washington-based public interest groups for the Justice Department to launch a sweeping antitrust probe of Google. The European Union and the state of Texas have reviews under way. Google says its rivals are fueling the attacks. Specifically, the company points to Microsoft, which has a stable of consultants and lawyers in Washington banging the antitrust drums.

“We try to create lots of new technologies for consumers, and the companies and industries that we disrupt sometimes try to seek recourse in Washington,” said Adam Kovacevich, a Google spokesman, who recently was detailed to deal solely with antitrust issues. “In particular, Microsoft and our large competitors have invested a lot in D.C. to stoke scrutiny of us. But our goal is to make sure that we can continue creating cool new things for consumers.”

Microsoft declined to trade barbs publicly but argues that Google is lashing out amid a growing number of complaints to regulators and lawmakers about the company’s business practices. The company points out competitors usually are the source of antitrust complaints.

One of Microsoft’s antitrust attorneys, Charles “Rick” Rule, of the international law firm Cadwalader, Wickersham & Taft, wrote in The Wall Street Journal in a September op-ed piece that Google is a monopolist and should face an investigation. “What goes around, comes around,” he wrote.

The war dance has continued to simmer and last year Google jumped directly into Microsoft’s home turf by announcing Google Chrome OS, its new operating system for PCs and netbooks. And while we’re still debating whether it will take down Windows or flop like a fish on land, we tend to forget that this isn’t the first time Google has challenged Microsoft. In fact, it’s become almost routine.

To be continued, 12 noon, today