Donald Trump has clearly fallen behind Ben Carson in Iowa.  And now a single national poll finds him falling behind Carson nationally, though with only one poll, that is hardly clear.

What can Trump do to get back into the lead?  For starters, let's talk about what he shouldn't do:

1) Pretend to be a devout Christian.  He's not.  The most ridiculous thing he's said recently is "I'm Presbyterian.  I'm a Presbyterian.  I'm a Presbyterian," as if saying it emphatically three times would make him sound devout.  It doesn't.  People laugh when he claims he carries a Bible around, and when he can't name a single phrase from it.   

2) Criticize Carson's religion.  After praising his own religion as mainstream, he purposely raises doubts about Carson's, saying he "doesn't know about it," to cast aspersions on it.  Why does he have to say anything about someone else's religion?  Criticizing someone else's religion is repugnant in America.  (Unless the religion, without naming names, is one that calls for the rest of us to be enslaved/killed.)

3) Yell at audiences something like, "Raise my poll numbers!  Raise my poll numbers!" as if it were a game, without giving them any reason to.  (Yes, he really did this!)

4) Claim that Carson used to be liberal, something that one could go on and on and on about when talking about Donald Trump.

Now what he can do:

1) He caught everyone's attention talking passionately and somewhat directly about immigration.  It is clear at least that he will build a wall, which is more than I can say for any of the other candidates except Ted Cruz.  He has also talked directly about keeping Muslim refugees out and about gun rights.

Why can't he, you know, talk directly about other issues?  It's not as if there aren't any others to talk about: abortion, the debt, over-regulation, a runaway Supreme Court, just to name a few.

2) Accept the fact that he isn't going to win over the majority of social conservatives. That isn't his strongest group.  It used to be, before people found a candidate they liked better: Ben Carson.

3) Don't worry about Ben Carson.  He will never, ever be the nominee.  It is extremely rare for a non-politician to be the nominee.  Donald Trump would be unusual enough, but at least he can credibly say he has superior skills as a negotiator.  Ben Carson has no direct skills or experience that would relate to the presidency.  He's also too soft-spoken.  He will peak and decline, though he may still win a plurality in Iowa.  His trajectory will be much more like Mike Huckabee and Rick Santorum (winners of Iowa) than George W. Bush and Bob Dole (also past winners).

4) If you want to criticize Carson, criticize him for his lack of negotiating skills and leadership ability.  Because it's so true that it will resonate with voters.  But Carson will probably rise and fall on his own.

5) Focus on Marco Rubio and Jeb Bush and Ted Cruz.  They are your real adversaries.  I predict, in fact, that Ted Cruz ultimately will be your biggest competition, as unlikely as it seems now.  Jeb is tarnished by his name and amnesty, and Marco is an obvious lightweight.  Cruz has gravitas, a lot of money, and a dedicated organization behind him, and he's an excellent debater.

Donald Trump can still win, if he focuses on the right issues and the right targets.

This article was written by Ed Straker, senior writer of NewsMachete.com, the conservative news site.