JACKSONVILLE, Fla. -- A day after Jeb Bush's campaign said it was taking major steps to cut costs, Donald Trump needled his Republican presidential rival, telling a crowd here Saturday that the former Florida governor is mounting a "failing campaign."

"Here's a guy who wants to run our country and he can't even run his own campaign," Trump told supporters at a sun-drenched riverfront rally where he spoke for nearly 90 minutes. Toward the end of his speech, the crowd near the back started thinning out.

Trump, whose rise has been a serious and unexpected complication for Bush's campaign, was wrapping up two-day swing through Florida, where Bush served two terms. An enthusiastic crowd started lining up Saturday morning for the afternoon event.

Among other things, Bush is reducing his campaign payroll by 40 percent. Campaigning in South Carolina on Saturday, Bush reportedly took sharp aim at Trump.

"If this election is about how we're going to fight to get nothing done, then … I don't want any part of it," Bush said, according to CNN. "I've got a lot of really cool things I could do other than sit around, being miserable, listening to people demonize me and me feeling compelled to demonize them. That is a joke. Elect Trump if you want that."

A day after contending with repeated interruptions by protesters in Miami, Trump did not encounter the same level of resistance in Jacksonville. The most notable push-back was a "Dump the Trump" banner hanging from a nearby bridge.

As Trump took the stage, an airplane flew overheard with a banner in tow reading "Trump!" and an American flag. A boat bobbed in the background of the rally with a sign that said "Save your rump vote for Trump."

Trump also kept up his criticism of other contenders, including Ben Carson, who polls show has overtaken Trump in Iowa recently.

"Carson is lower energy than Bush. I don't understand what's going on," he said.

The real estate mogul labeled Sen. Bernie Sanders (I-Vt.)  a "communist," and he slammed former secretary of state Hillary Rodham Clinton and Florida Sen. Marco Rubio (R).