Sen. Ted Cruz on Sunday defended flipping his vote on a crop insurance measure last year, blaming procedural confusion for an action rival Sen. Marco Rubio blistered him over at Thursday night's Republican debate.

"In that instance they had flipped the order of votes, and so I went up voting initially, believing we were voting on cloture, on the Export-Import Bank," Cruz told host Chris Wallace on "Fox News Sunday."

Cruz complained after Wallace showed a video of the Texas senator voting against the amendment to a federal spending measure passed last year, then returning to the Senate well to reverse himself.

The vote pitted farm-friendly Republicans against fiscal conservatives who consider the $3 billion crop insurance program a wasteful subsidy.

"I appreciate you passing on other campaigns' oppo hits," Cruz said. "But [that vote] was based on a factual mistake."

Cruz said Sen. Pat Roberts, R-Kan., and his own staff alerted him to the mistake.

Roberts has disputed that account, Wallace noted. Cruz reversed course after Roberts told him "This will hurt you in Iowa," according to the Kansas senator.

"Pat said this was about crop insurance, and I was completely puzzled," Cruz explained, without disputing that Roberts mentioned the Iowa caucuses.

Rubio launched an attack on Cruz over the reversal during the debate, saying it shows Cruz's frequent attacks on the "Washington cartel" are hypocritical.

"This is one of the political games people play," Cruz said Sunday, insisting his switch was not a calculated pander.