The Republican Party will owe The Donald, big time, if their candidate wins the general election.  President Rubio or President Cruz should give him a suitable reward – how about secretary of homeland security, with instructions to build a wall, seal the border, and, for starters, deport unvetted Syrian refugees and criminal illegals?

In part because of Trump, no Republican will win the nomination unless he convinces voters that he will exercise control over our borders.  Unless this threshold is met, no nominee will be in contention.  For 30 years we've demanded the federal government stop illegal immigration, and for 30 years we've been lied to, starting with Bush 1.  That ends next year.  If neither Cruz nor Rubio is judged honest and credible on this issue, Trump could be the nominee himself.

This one issue, immigration, could win the election.  It is the key to the white non-college-educated vote.  If they turn out for Cruz or Rubio, the way they did not for Mitt Romney, the mythical blue electoral wall is broken, and the Republican Party will notch a historic win.

Again in large part because of Trump, this country is having a serious conversation about our refugee policy.  It is long overdue.  Today it's Syrians.  Tomorrow we could see a refugee crisis in Libya, or Kurdistan, or Nigeria, or Somalia, or Haiti, or Pakistan.  The Third World is teeming with desperate people whose only hope of the good life is entry to the West.  What is our obligation to them?  How many can we admit?  Who should be allowed in, and who should be denied?  What circumstances justify bringing groups of desperately poor, and economically backward, people who share virtually nothing with our culture of tolerance and individual freedom?

We haven't had this discussion until now, because the ruling elite would rather make these kinds of decisions without input from the unenlightened masses – i.e., voters.  This may well be one of the most important issues of the 21st century.  And the third of the country that follows Trump will insist, and a majority of the electorate will agree, that the primary consideration in any such decision will be – what is in the best interest of the American people?  How we handle the Syrians is setting a precedent.  We have to get this right.

The upcoming election is set up to be a Republican landslide, provided we avoid splitting the vote with a third party.  This has always been the greatest threat posed by Trump.  If he announced tomorrow that he is running as an independent, Hillary will immediately be the odds-on favorite.  His pledge of loyalty at the Las Vegas debate was, at least in part, due to The Donald's feeling that he is, in fact, being treated with respect.  He says this is very important to him.  Why don't people believe him?  When Cruz responded with humor to being called "a bit of a maniac," he did himself, and the party, a favor.  When Trump says treat me nice, he means it.  Let's all bear this in mind.

With the extremely disappointing omnibus budget bill this week, congressional Republicans have again enraged large swathes of the American people.  They have stained the Republican brand so badly that conditions are ripe for a third party, or another Ross Perot.  But The Donald already occupies that space, dominates it, and there's not going to be a third party without him.

This is why Donald Trump is the Indispensable Man of this election cycle.  He is personally holding the urge for a third party at bay.  For all the vitriol he's subject to, all Republicans should say a prayer of thanks that Donald Trump is no Ross Perot.

The Republican Party needs Donald Trump a lot more than he needs it.

Fritz Pettyjohn is a former Alaska state legislator; the 1979-1980 chairman, Reagan for President, Alaska; and a co-founder of the Balanced Budget Amendment Task Force.  He blogs daily at ReaganProject.com.