TRENTON -- Hours after firing his campaign manager Monday, presumptive Republican presidential nominee Donald Trump suggested the move marks a new chapter in his so-far unconventional bid for the White House.

During an interview on Fox News' "The O'Reilly Factor," Trump heaped praise for Corey Lewandowski, who ran the first year of his campaign.

"I think Corey's terrific," the billionaire businessman and former Atlantic City casino mogul said. "He's a talented person. He's a good guy. He's a friend of mine."

But, Trump said, "it's time now for a different kind of a campaign" as he prepares for the general election against presumptive Democratic nominee Hillary Clinton.

"We ran a small, beautiful, well-unified campaign," he said. "It worked very well in the primaries. I think I'm probably going to do some of that (in the general election.)"

"But we're going to go a little bit of a different route from this point forward," Trump added. "A little different style."

Lewandowski was at the helm as Trump shattered expectations by barnstorming past 16 opponents -- including New Jersey Gov. Chris Christie -- in the GOP primary. Trump did so despite making controversial statements about illegal immigration and Muslims and despite having a small staff and a small fundraising operation.

All the while, Lewandowski's mantra was simple: "Let Trump be Trump."

But Lewandowski was was abruptly fired Monday amid fears from some Republican leaders and donors that Trump needs to change his tone, raise more money, and craft a more traditional-looking campaign to battle Clinton and appeal to a wider array of voters.

In an interview with CNN, Lewandowski himself said Trump's campaign "needs to continue to grow to be successful."

Recent polls have shown Clinton widening her lead over Trump.

But on Monday, Trump dismissed the surveys, saying it's too early to tell how the race is shaping up.

"I think it's very close," he told host Bill O'Reilly. "It's fairly early to have polling. I think we haven't even gotten started yet."

Brent Johnson may be reached at bjohnson@njadvancemedia.com. Follow him on Twitter @johnsb01. Find NJ.com Politics on Facebook.