Republican insiders believe that there is a virtual certainty that the GOP convention will require multiple ballots to choose a nominee.

Members of the Politico Caucus – group of GOP campaign operatives, activists, and strategists – say the chances of a contested convention are rougly 90%.

It’s a marked shift from a month ago, when just half of insiders were predicting a contested convention. Since that time, Trump has romped to victory in states that awarded all their delegates to the winner, like Florida and Arizona. But Cruz bounced back this week in Wisconsin — and is also dominating in states like North Dakota, Colorado and Wyoming, where party insiders, not rank-and-file voters, pick the delegates.

Cruz’s victory in Wisconsin, where he won 36 of the 42 delegates at stake, narrows Trump’s path to the nomination. Trump’s path is also impaired by his precipitous fall in national polling, which hurts the New York real estate tycoon’s standing among both Republican voters and convention delegates who want to nominate a strong general-election candidate.

“Donald Trump has one chance to win the nomination, and that is on the first ballot. Right now, I put his chances at about 40 percent, and that will require him to get some number of delegates from the unpledged delegates in states like North Dakota, Colorado, Pennsylvania, and a few territories,” said an Iowa Republican, who, like all respondents, completed the survey anonymously.

But while that Iowa Republican sees Trump performing well in upcoming primaries in New York, Connecticut, Pennsylvania and other Northeastern states later this month, the Republican warned that the map is less favorable in May.

“Of course, he will run up the score in the Northeast and have some April momentum, but there are good states ahead for Cruz as well, such as Indiana, Nebraska, and possibly Washington and Oregon. He's also dominated the delegate selection process in a whole host of states where they are pledged,” the Iowa Republican added.

Some insiders gave Trump, who needs to win just under 60 percent of the remaining delegates to clinch the nomination outright, an outside chance to win on the first ballot — but only if he overperforms in the upcoming states.

One Florida Republican pointed to the fact Trump’s been outgunned in recent states — including in Wisconsin, where his opponents and anti-Trump groups outspent him by a more than 10-to-1 ratio in television and radio advertising.

While Trump definitely has the advantage in April's northeast corridor primaries, Cruz is playing the delegate roundup game to perfection.  The Texas senator is picking off uncommitted delegates in states won by Trump and making a strong play for unbound delegates in states like Colorado and North Dakota.  This delegate-wrangling will keep Cruz in the race through the last primaries in June.

I don't necessarily agree that Trump is doomed if he doesn't win on the first ballot.  The urge to unify the party is strong, and if Trump arrives in Cleveland less than 100 votes short of the nomination, there may be a surge to put him over the top in order to avoid a bloody convention fight.  Rubio and Kasich delegates may be key in this regard, as they would hold the balance of power for Trump on a second ballot, when they would be free to vote for anyone they choose.

All bets are off if Trump can't make it by the second ballot.  At that point, both Cruz and Trump are likely to start bleeding support to another candidate or candidates, throwing the convention into chaos and into the abyss of the unknown. 

A recipe for disaster in November.