Former New York City mayor Rudy Giuliani (R) says he knows that lower taxes yield more revenue.

In his latest TV ad, Giuliani says Democratic presidential hopefuls Sen. Hillary Rodham Clinton (N.Y.), Sen. Barack ObamaBarack Hussein ObamaMcCarthy: ‘No deadline on DACA’ Democrats will need to explain if they shut government down over illegal immigration Trump’s first year in office was the year of the woman MORE (Ill.), and former Sen. John Edwards (N.C.), "are making the promise to raise taxes."

"The only thing I can tell you in addition to that is they'll raise taxes even more then they promise," Giuliani says.