Donald Trump has come under fire for comments he made about abortion over 15 years ago. Two Super PACs supporting Texas Senator Ted Cruz has issued a challenge to Trump to debate his comments on the issue.

Keep the Promise I and Keep the Promise II Super PACs have also offered $1.5 million for veterans if Trump debates Cruz directly in Iowa before Sunday, January 31. In the press release about the challenge, as reported by Breitbart, the main donors of the Super PACs, the Mercer and Neugebauer family, tried to sell the debate as a way to generate money for veterans.

"Senator Cruz and Mr. Trump both respect the veterans and hold them in the highest regard but Senator Cruz respects the process and we are calling on Mr. Trump to do the same and debates are the purest form of democracy. Iowans - and Americans - deserve to hear from the frontrunners in this 'two-man race' one last time.  Not only would this be a heck of a debate, but it would also be a terrific opportunity to generate millions of dollars for the veterans."

Keep the Promise I questioned Trump in an ad, citing comments he made during a television appearance in 1999. Trump stated that he was "pro-choice in every respect." However, in his recent op-ed in the Washington Examiner in January, Time reported Trump's clarification on his opinions.

"Let me be clear - I am pro-life. I support that position with exceptions allowed for rape, incest or the life of the mother being at risk. I did not always hold this position, but I had a significant personal experience that brought the precious gift of life into perspective for me."

The terms of the debate are specific: one on one between Trump and Cruz, for one hour in Iowa, before the 31st, with the moderator mutually chosen. Cruz has even stated that they have a venue and time already in place.

Even Carly Fiorina, another candidate for the Republican nominee, decided to add to the challenge. Fiorina tweeted that she would give $1.5 million to veteran's charities if Trump joined the main Republican debate in Sioux City and $2 million if he would meet her a Drake University on January 29 to debate her.

Not surprisingly, veterans' groups were not happy to be exploited for political pettiness. Vox citied a tweet from the founder of Iraq and Afghanistan Veterans of America saying, "If offered, @IAVA will decline donations from Trump's event. We need strong policies from candidates, not to be used for political stunts."

Despite all the pressure, the Trump camp has declined the offer, but has stated that if the race comes down between Trump and Cruz that he would be happy to debate him. Trump has already announced that he will also skip the GOP debate because of a feud with the debate host.