- Trump is in second place in the Iowa polls behind Walker
- Trump's remarks come one day after a fundraiser for Walker's campaign called Trump "DumbDumb"
(CNN)Donald Trump has spent much of the early days of his presidential campaign taking on Jeb Bush.
But in Iowa on Saturday, the real estate mogul took shots at Scott Walker, who's long stood atop polls in the Hawkeye State, home to the critical first-in-the-nation caucuses.
Trump -- who is in second place in Iowa polls behind Walker -- slammed the Wisconsin governor's leadership.
"Wisconsin is doing terribly. It's in turmoil," Trump said at Oskaloosa High School in Oskaloosa. "The roads are a disaster because they don't have money to rebuild them."
He also accused Walker's administration of borrowing due to a budget deficit, and painted him as a supporter of Common Core education standards, which are opposed by much of the Republican base.
"Schools are a disaster. Hospitals and education are a disaster," Trump said. "And he was totally in favor of Common Core, which I hate."
Walker recently has been a fierce opponent of Common Core, leading Trump on Saturday to label him a flip-flopper.
A Monmouth University poll of Iowans released Monday and conducted over last weekend showed Walker continues to maintain a solid lead in the Iowa Republican caucus, though Trump has gained an edge over the rest of the field and now stands alone in second place.
Of likely caucus attendees, 22% told pollsters that they'd support the Wisconsin governor in next winter's matchup, but 13% said they would back Trump, who has suddenly catapulted to the front of some national polls. Trump only earned 4% of Republicans' support in a Des Moines Register/Bloomberg survey conducted in May, a month before Trump announced his campaign and made a string of controversial comments that came alongside his rise.
Trump's remarks come one day after a fundraiser for Walker's campaign called Trump "DumbDumb."
Gregory Slayton, a New Hampshire venture capitalist who served in the George W. Bush administration, challenged Trump's intelligence in a fund-raising invitation, The Wall Street Journal reported Friday.
"As you've seen Gov Walker is now well ahead of everyone not named DumbDumb (aka Trump) in the national polls," the email invitation said.
Slayton told the paper that intelligence is not required to gain the wealth that Trump has acquired.
"I didn't mean that to be public but obviously I stand behind it," he said. "Look, this is a great country. Guys who are not that smart can get rich, it's wonderful. But Donald Trump is not going to be president of the United States ever, period, end of story."
Also on Saturday, Trump made reference to the Des Moines Register, to which his campaign denied press credentials following a negative editorial this week in which the paper called for Trump to drop out of the race.
"We have so many people standing outside ... actually, the Des Moines Register is standing outside, too," Trump said, to laughter.
Jennifer Jacobs, the Register's chief political reporter, tweeted that Henry Hahn, another reporter for the paper, was in the main auditorium covering the event. She said the campaign staff was polite to her earlier Saturday, but that the candidate himself was "silent" when he saw her.