Trump's comments came during a speech at the Family Leadership Summit in Ames, Iowa, along with former Sen. Rick Santorum, R-Pa., and Sen. Ted Cruz, R-Texas, two other potential White House hopefuls, The Hill reported.
"If I made a decision, I'd spend a lot," said Trump, who has estimated his net worth at $10 billion. "If I did it, I'd spend whatever it took."
On Saturday night, Trump predicted that Hillary Clinton will be the Democratic nominee for president in 2016, the Des Moines Register reported.
Trump said he knows Clinton "very well," and that Republicans need a fierce candidate if they want to beat her.
"It's going to be, in my opinion, a tougher race than the last race," Trump said. "Really tough. And somebody's going to have to emerge who's really strong. The Republicans have to do what's right. If they don't pick the right person -- it's got to be the perfect person -- they are going to get drubbed in the 2016 election."
Trump also said that he believes an immigration reform bill that was passed in the Senate and is now sitting in the House of Representatives "could be a death wish for the Republican Party," because it could pave the way for millions of undocumented immigrants to get the right to vote.
"Every one of those people -- virtually -- will be voting Democratic," he said. "They're not voting Republican."