So, Mr. and Mrs. GOP “establishment,” you want to “stop” Donald Trump at a contested convention? Maybe with a nice moderate guy like John Kasich? Really? Just know that "contested" would mean "stolen" to vast numbers of disaffected party members and Trump and Sen. Ted Cruz supporters. The party would shatter, the faithful would stay home in November, and the nation would elect Hillary Clinton president.

In other words, denying the nomination to someone who comes close to the necessary 1,237 delegate votes and giving it to an also-ran would be unfair and suicidal.

Now, a nomination fight between two top contenders who both arrive at the convention just short of the magic number, that’s fair. Only Cruz can beat Trump or at least make it close and keep him short of 1,237.

Recently, former Massachusetts governor and failed 2012 Republican presidential candidate Mitt Romney invoked Ronald Reagan’s phrase “a time for choosing.” For Republicans, the time is now, not next week. The choice is Trump or Cruz. About 100 delegates separate them. Both can reach 1,237 or come very close. Neither Sen. Marco Rubio nor Ohio Gov. John Kasich can.

Today, Trump has about 460 delegates. To get to 1,237 delegates, he needs 777 more, or 61 percent of the approximately 1,265 delegates in the contests now remaining. With about 360 delegates today, Cruz needs 877 more, or 69 percent of the remaining delegates. Both men face difficult but achievable challenges.

Kasich and Rubio face impossible tasks, with too few delegates too late in the game. They cannot secure the nomination prior to the convention or even make it close. If Rubio loses Tuesday in his home state of Florida, which appears a certainty based on the polls, he is done and should recognize as much and drop out.

For Kasich, his candidacy is predicated on winning Ohio Tuesday — which polling indicates might well happen — then hanging in there and betting the delegates at the convention will reject the will of the voters in the primaries and nominate him over Trump or Cruz despite what will be his relatively small delegate count. If that happened, it would be fundamentally unfair and undemocratic. It’s delusional.

By sticking around, Kasich − and Rubio if he is stubborn enough to continue after losing Florida − will further enable Trump's nomination by continuing to split the anti-Trump vote.

The “GOP establishment” is right that the majority of the GOP is anti-Trump. The just-released NBC/Wall Street Journal poll shows that, in states with upcoming contests, only 30 percent of GOP voters favor Trump. And only a plurality has voted for him to date. But that anti-Trump vote remains split – going forward 27/22/20 among Cruz, Kasich and Rubio, according to the poll.

Normally, winners become more victorious the more they win. Trump has not. After 14 primary victories, he has not yet expanded his vote share. He hasn’t won any contest with a majority. Normally, someone who wins but doesn’t grow his winning margin begins to fade. Donald Trump has not. He has a rock solid base of support that provides him a consistent narrow margin of victory.

If all the remaining states awarded delegates proportionally, none of the four candidates would get close to 1,237. A series of elimination votes at the convention would be inevitable and manifestly fair.

However, in winner-takes-all contests, a candidate with Trump’s 25 percent to 35 percent share can win 100 percent of the delegates, meaning Trump is very likely to arrive at the convention at or within shouting distance of the winning 1,237 – without ever attracting the support of a majority of GOP primary voters.

As things stand now, the GOP is on track to nominate a candidate it does not support.

On Wednesday morning, we are likely to find that Trump has won Florida’s 99 delegates and Kasich Ohio’s 66, and that Cruz has won Missouri’s 52 delegates, given that the Show Me State is surrounded by states in which Cruz has won or placed a very close second, and, finally, that Trump has won Illinois’ 69, as polls seem to be predicting.

If so, the delegate counts (excluding the 72 awarded proportionally in North Carolina) would be approximately: Trump 630, Cruz 415, Rubio 150 and Kasich 120 with only about 900 delegates available in the then remaining contests. Trump would need 67 percent of remaining delegates to secure the nomination, Cruz a daunting 92 percent. But Cruz could keep it close.

So, Mr. and Mrs. GOP “establishment,” your only plausible stop-Trump option is Cruz. Get behind him – now. If he were to win Illinois Tuesday, that would further shift the calculus in favor of his blocking Trump.

You may not like Ted Cruz and he may not win in November, but he won’t destroy the chances of every down-ballot Republican candidate, as would Donald Trump or John Kasich, whose selection by convention machinations would blow the GOP to smithereens.

Red Jahncke is president of The Townsend Group Intl, LLC. RTJahncke@Gmail.com and an occassional contributor to theday.com.