HermanCain has made 9-9-9 the centerpiece of his campaign. And now economists and elected officials, from the left and right, are giving it much closer scrutiny, some even arguing that it would be a tax increase.

In an interview Friday afternoon on CNN’s Situation Room with Wolf Blitzer, Sen. John McCain (R-Ariz.), the 2008 Republican presidential nominee, voiced the same concerns.

Sen. John McCain, R-Ariz. . (AP Photo, File) (AP)

On the show, McCain said that he wasn’t prepared to endorse any candidate in the GOP race, and that he would take a closer look at Cain’s plan, which has also drawn criticism from the private sector.

Cain argues that the plan will grow the economy by five percent.

The former Godfather’s pizza CEO has found one powerful fan in House Budget Committee Chairman and GOP ideas man Paul Ryan (R-Wis.), who in an interview with the Daily Caller said he “loves” Cain’s approach to reforming the tax code.

“We need more bold ideas like this because it is specific and credible,” Ryan said. “I’m more of a flat-tax kind of a guy.”