Donald Trump in an appearance on Fox News' "The O'Reilly Factor." Fox News Donald Trump told Bill O'Reilly on Monday that he plans to run "a different kind of a campaign" after firing campaign manager Corey Lewandowski earlier in the day.

Speaking on Fox News' "The O'Reilly Factor," the presumptive Republican presidential nominee praised Lewandowski, but suggested that he'll be ramping up his operations ahead of November's general election.

"He's a good guy. He's a friend of mine. But I think it's time now for a different kind of a campaign," Trump said.

"We ran a small, beautiful, well-unified campaign. It worked very well in the primaries," Trump added. "But we're going to go a little bit of a different route from this point forward."

Trump's campaign is reportedly focusing on hiring more staffers ahead of the election, an area in which he badly trails his presumptive Democratic rival, Hillary Clinton.

According to an Associated Press report, the Trump campaign has about 30 paid staff members on the ground across the country, an unusually low number for a candidate.

Meanwhile, Clinton has hired 50 staff members in Ohio alone.