Herman Cain's 9-9-9 plan is designed to appeal to proponents of lower taxes. But the king of the proponents isn't impressed.

Grover Norquist, the president of the advocacy group Americans for Tax Reform, whose anti-tax pledge has become one of the most powerful litmus tests for Republican legislators, said on Monday that he would not support creating new types of taxes, even with lower rates.

Cain's plan would scrap the current tax code and replace it with three flat taxes: a 9 percent personal income tax, a 9 percent corporate tax and a 9 percent national sales tax. Eventually, he wants to swap out all three of those taxes in favor of a single consumption tax, or fair tax, but given how difficult it is to revamp the tax code even once, the 9-9-9 structure would probably be in place for a long time -- and the rates wouldn't necessarily stay at 9 percent.

That, Norquist says, is the fatal flaw in the 9-9-9 plan: Instead of having one tax that could increase, we would have three.

It gives you three taxes, all of which could grow, he told CNN. You will have put three needles in your arm to draw blood instead of one.

Norquist got even more descriptive on ABC News' Top Line on Monday, comparing the 9-9-9 plan to having tapeworms.

To put tapeworms in your tummy to try and maintain your weight -- they may have their own idea about their growth patterns and what they want to do, he said. Creating new taxes is a very dangerous project.

He said a better solution would be to just take the present system and prune it back like a rose bush.

Some tax policy experts agreed with Norquist.

Politicians have done a really bad job with one source of tax revenue, the personal income tax, Daniel Mitchell, a senior fellow with the libertarian Cato Institute, told the International Business Times. Imagine giving them three sources of revenue. That, to me, would be very dangerous, because we see from the experience in Europe that politicians wouldn't keep it 9-9-9.

In a recent Fox News interview, Chris Wallace asked Cain to address that criticism, and Cain responded that he would keep the rates at 9-9-9 by requiring a two-thirds supermajority in the Senate to raise taxes -- but the constitutionality of that is questionable.

Other experts said there was no way to eliminate the possibility of increased tax rates.

It's certainly a risk, Will McBride, an economist with the nonpartisan Tax Foundation, told IBTimes, but that's the history of taxation.