God-o-Meter notes that Paul Weyrich speculates that Thompson’s endorsement makes no sense and is the product of payola:

Paul M. Weyrich, president of the Free Congress Foundation, said the endorsement “makes no sense,” and speculated that it had been motivated by money.
“I think in all probability the Thompson people were engaged with the National Right to Life people in financial dealing,” said Mr. Weyrich, who has endorsed former Massachusetts Gov. Mitt Romney for the Republican nomination.
“In the past, the Republican Party has funded National Right to Life, and while the committee can raise money on its own, it needs funding” from outside sources.

Does he have proof of this allegation because this just sounds like bearing false witness if he doesn’t.
Thompson’s endorsement makes perfect sense when you look at his voting record and see that he has always voted in favor of life and he also supports the ban on funding embryonic stem cells.
And as far as the federal amendment goes, let me ask you this: what candidate has laid out a strategy to get such an amendment? Who is going out on a limb to say that they’ll make it happen? What candidate would actually tell NRLC that he is the candidate for them because he knows he can convince enough pro-choice Senators to support it?
BTW, poor Thompson lost a point on the God-o-Meter for this slander, it really doesn’t seem fair since it hasn’t been proven that he gave NRLC money.