Republican Presidential candidates Donald Trump and Ted Cruz are warring over their wives.

FOX's Rachel Sutherland reports from Washington:

Trump and Cruz have been having late-night Twitter fights over viral pictures of their wives. An old photo of a scantily-clad Melania Trump and a less-than-flattering image of Heidi Cruz.

The feud devolved into this statement from an incensed Ted Cruz at a Wisconsin factory:

(Cruz) "Donald you're a sniveling coward. And leave Heidi the hell alone."

Trump says he didn't start it, saying Cruz knew a super PAC was putting out the picture of Melania Trump. An anti-Trump super PAC ran has been running an ad featuring women reciting derogatory comments made by the billionaire.

In Washington, Rachel Sutherland, FOX News.