He thinks voters will be happy that he's "cutting taxes", but he's wrong. Those payroll taxes are the only funding that Social Security gets, and eliminating them would completely defund the Social Security program. It's not a tax cut -- it's a backdoor attempt to destroy the Social Security program (and Medicare also).
Republicans have always opposed Social Security, and have tried many times to destroy the program. This is nothing more than Trump's sneaky way to accomplish that.
I'm not the only one who believes that. The following is a statement from Nancy Altman, the president of Social Security Works.
“Donald Trump once promised that he would be ‘the only Republican that doesn’t want to cut Social Security.’ We now know that what he meant is that cutting Social Security doesn’t go far enough for him: He wants to destroy Social Security. Donald Trump’s executive order, which seeks to defer Social Security contributions, is bad enough. But his promise to ‘terminate’ FICA contributions if he is reelected is a full-on declaration of war against current and future Social Security beneficiaries. Social Security is the foundation of everyone’s retirement security. At a time when pensions are vanishing and 401ks have proven inadequate, Trump’s plan to eliminate Social Security’s revenue stream would destroy the one source of retirement income that people can count on. Moreover, Social Security is often the only disability insurance and life insurance that working families have. If reelected, Trump plans to destroy those benefits as well. Every member of Congress must speak up now to denounce Donald Trump’s unconstitutional raid on Social Security. Voters should treat any Senator or Representative who is silent as complicit in destroying Social Security. Furthermore, every American who cares about Social Security’s future must do everything they can to ensure that Trump does not get a second term.”