In his final speech before Iowa caucus day, Donald Trump renewed his old promise to build a lavish White House ballroom and pay for it himself.

“Every time the top people come over from China … they put up a tent at the White House,” he said, during his final event Sunday in Sioux City, Iowa. “We’ll have a ballroom at the White House.”

He said he had long ago come up with a plan for the new facility. “We’ll get the top people, the top everything, we’ll have the best ballroom. Because I notice they always put tents up on the lawn. Number one, it’s not a good security thing. Number two, the guy that owns the tents is making a fortune,” he said.

Trump said he once called David Axelrod, a former senior adviser to President Obama, offering to build a ballroom worth “at least $100 million” for free. “We’ll put it someplace so it works contextually, magnificently,” Trump said of his construction offer. “I never heard back.”

Contacted by TIME Sunday night, Axelrod confirmed that Trump had contacted the White House about a ballroom. “He did offer to build one,” Axelrod confirmed to TIME in an email. “I don’t recall him saying he would pay for it. I passed his offer along to the social secretary.”

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This was not the first time Trump had made a new addition to the White House an issue in connection with his own presidential run. As far back as 2011, when Trump was flirting with a presidential campaign against Barack Obama, Trump had floated the idea of a White House ballroom on the Rush Limbaugh radio program. “We’ll go through committees. We’ll pick the one they like. We’ll pick the architect everybody likes. We’ll pick something that works. We’ll do 10 designs,” he said of his offer to the White House. “You’ll pick the one that’s the greatest with the greatest architecture. I will build it free. So that’s anywhere from 50 to 100 million-dollar gift. I will give that, and I mean, I’m talking, Rush — it’s the first time I’ve said this. I’m talking to the biggest person, one of the biggest people at the White House. I’m not talking to a low-level person.”

At his final event, Trump also attacked his main rival Texas Senator Ted Cruz during the Sioux City appearance, knocking him for a controversial mailer his team sent out designed to look like an official government document. “It’s so terrible, I’ve never seen anything like it,” Trump said. “It’s a fraud as far as I’m concerned.”

The latest Des Moines Register poll, released Saturday, found that Trump was leading the delegate race in Iowa, with 28% of likely caucus goers, compared with 23% for Cruz.

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Write to Tessa Berenson at tessa.berenson@time.com.