Grover Norquist, seen as the preeminent anti-tax guru amongst conservatives, has expressed skepticism over Herman Cain’s 999 tax plan, calling it "dangerous."

Norquist is president of Americans for Tax Reform, a taxpayer advocacy group, and over the years he has powerfully commanded the allegiance of congressional Republicans through signed pledges in which they promise to never raise taxes.

 Norquist is uneasy over the potential for Cain’s 999 plan to open new avenue for taxation, something that would go against his well established principle of keeping tax rates low.

Cain's 999 tax plan would eliminate today’s current tax structure and replace it with a 9% income tax, a 9% corporate tax and a 9% national sales tax.

Despite the fact that Norquist looks favorably on lower overall rates, he abhors even the suggestion of new taxes.

Norquist reportedly had this to say Monday concerning Cain’s tax plan: "If it was coming up for a vote tomorrow, I would not support it," according to CNNMoney.

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He believes that Cain’s plan offers three new tax categories that could all grow and said, "You will have put three needles in your arm to draw blood instead of one."

Due to the proposition that "999" is revenue neutral, meaning the government would take in the same total dollar amount in taxes it does now, Norquist believes Cain's "999" does not technically undermined his "Taxpayer Protection Pledge."

But Norquist is also leery of the second phase of Cain's plan, which he believes is GOP presidential hopeful's intention to have the country adopt a flat tax.

A fair tax is akin to a national sales tax, or VAT. Consumers would pay federal tax on what they spend rather than on what they earn, save or invest.

Norquist is opposed to adopting a VAT, and cites what he feels is Europe's unsuccessful experience with the tax as a reason for avoiding it.

In an appearance on ABC News Monday, Norquist called Cain's suggested tax plan "very dangerous."