Nearly everyone predicted that the silly season that engulfed the Republican primary would end once it was clear that Mitt Romney would be the GOP nominee for president. But Romney's duet with real estate celebrity Donald Trump tells us otherwise.

Trump has returned with another episode of birther babble. He has been saying on television shows recently that millions of people still believe that President Obama is not an American citizen because major questions about his birth records have gone unanswered.

I guess we shouldn't be surprised. Many people once believed that President Kennedy was living in a Dallas hospital in a vegetative state.

Regardless of what people believe about Kennedy or Obama, Romney's hookup with Trump is troubling. Trump is a Romney surrogate who has thrown lavish fundraising events for Romney, and his voice is heard on political robo-calls on Romney's behalf. Their relationship is a reflection of the kind of businessmen the two are, and it offers some insight into what kind of president Romney might be.

Either Romney knows that the birther stuff is nonsense or he believes it, too. He could gracefully distance himself from the party's more radical fringe, or he could denounce it. Instead he has become a silent partner, a co-producer of crazy rumors intended to bring down a US president.

Ordinarily, I would sing the praises of persistence. Persistence can often outweigh talent, and I have to hand it to Romney. He has been after this job for the better half of the last decade. But he's already shown that he'll say almost anything to win the election, prompting Washington Post columnist Eugene Robinson to describe him as a "liar."

The association with Trump shows Romney will do almost anything, too.

And as the silly season continues, it's giving the American public a good look at what a Romney White House would look like, and who would be in there influencing policy.