It would be a long shot to happen, but the Saturday campaign event by Republican presidential candidate Ted Cruz in Sioux City could get really interesting. Perhaps a $1.5 million offer sweetens the pot.

Republican candidate Donald Trump has pulled out of the final candidate debate prior to the Monday Iowa caucuses, which plays out Thursday night in Des Moines. Trump is feuding with Fox News, and since that news network is hosting the debate, Trump won't take part.

Cruz had previously set a Saturday event at Western Iowa Tech Community College in Sioux City. Now, he has asked Trump to come to WIT and debate one-on-one. If it happened, Sioux City would be at the epicenter of national politics in two days.

In a letter to Trump, Cruz wrote: "We owe it to the men and women of Iowa to ensure that they hear jointly and directly from the two leading Republican candidates so that they may contrast our positions on the critical issues we face as a nation as they make their final choice leading up to Monday’s caucuses.

"Accordingly, please accept this invitation to join me at an in-person, two-hour Town Hall event at Western Iowa Tech Community College in Sioux City this Saturday, January 30th at 8:00 p.m. Central. This venue is already reserved and I would propose that our campaigns evenly divide available seating/ticketing."

There is a new wrinkle Thursday morning. A super political action committee, Keep The Promise, has offered to donate $1.5 million to veterans charities if Trump takes Cruz's debate offer.

Keep The Promise hashtagged a tweet with the phrase #greatdeal : "@realDonaldTrump: debate #TedCruz one-on-one in Iowa before the caucuses and we will donate $1.5M to vet charities."

Trump had a tweet to respond to the Cruz offer: "Even though I beat him in the first six debates, especially the last one, Ted Cruz wants to debate me again. Can we do it in Canada?"

Trump's schedule shows he will be campaigning in Davenport about the time Cruz will be in Sioux City on Saturday.