U.S. Rep. Beto O'Rourke, the El Paso Democrat challenging Republican incumbent Ted Cruz in Texas' U.S. Senate race, says a proposed Aug. 31 debate between the two "is not going to happen."

"Friday in Dallas is not going to happen, but I'm convinced we will debate," O'Rourke said Monday during an appearance at the 2018 Texas Disability Issues Forum in Austin. "I'm convinced there will be a number of debates."

In July, Cruz challenged O'Rourke to five debates – sending a detailed plan with proposed dates, cities and topics. The first was to be on Aug. 31 in Dallas and to focus on "Jobs/Taxes/Federal Regulations/National Economy." O'Rourke accepted Cruz's proposal for five debates but suggested some revisions — including having a sixth debate in O'Rourke's hometown of El Paso.

In April, O'Rourke's campaign kicked off the debate negotiations by proposing six debates, including two in Spanish.

O'Rourke said Monday that Cruz's campaign has "attempted to dictate" different aspects of the debate schedule, such as the time, the moderators and which subjects the candidates could speak about.

"We're working through those differences, and we're trying to introduce more of a collaborative style to the negotiations than he may be used to," O'Rourke said during the forum. "And so we're confident that out of that, we're going to come to something good."

Cruz's team shot back Monday evening.

"[O'Rourke] begged for debates, but when Sen. Cruz invited him to five debates all across Texas, suddenly O’Rourke seemed to get scared," spokesperson Emily Miller said, adding that "except for when he has to be in DC for his work in the Senate, Cruz is ready and excited to debate O’Rourke, including this Friday."