One of the more perplexing questions of the 2016 race for President among Republicans has been the reluctance - and outright refusal - of outside Republican groups and most GOP candidates to run negative ads against Donald Trump.

Instead, a big chunk of money has been directed at Marco Rubio, who has emerged as the next most popular Republican behind Trump and Ted Cruz.

Most of the money going against Rubio has been from allies of another Floridian, former Gov. Jeb Bush, as his Super PAC Right to Rise has been after Rubio with big money.

That has left many conservatives aggravated with Bush and Right to Rise.

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Credit: Jamie Dupree

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Credit: Jamie Dupree

While $20 million has been dropped on Rubio, that same Super PAC has spent a minor amount on ads against Trump, as right now in Iowa, no negative ads are on the air against Trump.

Thursday night, a group of conservative writers banded together under the masthead of the National Review magazine, arguing that Trump is not the answer many conservatives are looking for.

Bush has also started to get into it with John Kasich, who has been bubbling up in New Hampshire, moving above Bush in the polls.

A Super PAC allied with Kasich turned out its own ad against Bush.

With 10 days until Iowa, most Repulicans are scrapping with each other on the air.

But not against Donald Trump. He remains a frontrunner who has been untouched by tough TV ads in the days before voters go to the polls.

That may help explain why he is the overall leader.