"I'm not a populist," Trump told reporters on Monday. "I'm a man of great common sense."

Trump would also eliminate the so-called marriage penalty and the estate tax. Single people earning less than $25,000 per year or married people earning less than $50,000 per year would pay no income tax, he said. Or as his plan posted online said, "They get a new one page form to send the IRS saying, "I win."

"There will be a major tax reduction," Trump told reporters, saying his plan would increase growth between 3 percent to 6 percent. "It'll grow the American economy at a level it hasn't seen in decades." 'Basic Conservatism'

Closing loopholes such as carried interest would fall in line with “basic conservatism and Republican orthodoxy,” economist Stephen Moore said in an interview prior to Trump's news conference.

“If Trump's plan is going to sell with supply-side economists, the tax rates across the board are going to have to come down,” said Moore, who has consulted with Paul and Bush on their tax plans and said he spoke to Trump's team about six weeks ago.

Trump has been the front-runner for the Republican presidential nomination for the past three months, but his lead in national polls has shrunk during the past 10 days. An NBC/Wall Street Journal survey released on Sunday showed him with a lead of just 1 percentage point over retired neurosurgeon Ben Carson.

Trump's lead has tightened since the second Republican president debate on Sept. 16, when he was the target of criticism from several rivals on stage, and was silent for long stretches as the discussion veered into policy issues. “He never really talks about issues, and can't have more than a 10-second soundbite on any key issue,” U.S. Senator Marco Rubio, a presidential candidate from Florida, said in a radio interview last week, adding that Trump was “not well informed on the issues.”

Republican voters, meanwhile, have said they trust Trump on economic policy. In a CNN poll of Iowa Republicans last month, Trump was picked as the best GOP candidate to handle the economy. In a Gallup poll in July, the only issue that a majority of Republicans said Trump would do a good job of handling was the economy.

'Next President'

Two Republican voters, Tricia Behne and Kathy Johnson from Delray Beach, Florida, stood in the crowd behind Trump on Monday, each wearing a red "Make America Great Again" cap. The two said they planned their trip specifically for a time when they might be able to see Trump speak.