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Story highlights

The Cruz campaign tried to get Rubio on board

Kasich tried to broach the subject with Rubio as well

(CNN) —  

Republican officials who oppose Donald Trump as their party nominee have spent the last few days – ever since the withdrawal from the race of Sen. Ted Cruz and Ohio Gov. John Kasich – wondering if there is anything they could have done to prevent this outcome.

Top officials of the Cruz campaign are convinced there is one specific step that could have stopped Trump – and they blame Sen. Marco Rubio for not taking that step.

In early March, it became clear that Trump was well on his way to the nomination and would even likely defeat Rubio in his home state of Florida’s March 15 primary. According to several sources close to Cruz, the Cruz campaign conducted several secret polls to see what the impact would be if Rubio joined Cruz as his running mate, with Cruz at the top of the ticket.

Politico reported in March that Rubio rejected the idea of a “unity ticket.” But the sources close to Cruz and Rubio are now offering a much fuller picture of the extent of Cruz’s polling, the reasons why Rubio said no, and the resentment the Cruz people have about Rubio’s rejection of the idea.

The Cruz campaign polled in three March 15 primary states, Illinois, Missouri and North Carolina – though not in Ohio, home to Kasich, or in Florida.

They also tested the matchup in a poll in Arizona, which would hold its contest on March 22, and in Wisconsin, which would hold its primary on April 5.

What did polls suggest a Cruz-Rubio ticket would do in those states?

“Blowout,” said a source close to Cruz. “65%-35%,” with Trump losing.

Through friends and emissaries, the Cruz campaign tried to get Rubio on board.

But Cruz could not reach him on the phone, and others reported back to the Cruz campaign that Rubio did not seem interested in having a discussion about this at all.

“He went off the grid,” said a source close to Cruz. Cruz campaign officials speculated that Rubio was interested in preserving his political viability for a contested GOP convention or the 2020 race.

A source familiar with Rubio’s thinking says there never really was a concrete offer from the Cruz campaign to team up – just vague discussions from donors about polls and the potential for such a move – but either way, he was not interested.

For one, the source said, Rubio thought the notion of two senators from Washington, D.C., teaming up against Trump would fit all too easily into the Trump outsider narrative. Second, Rubio was concerned that as a fellow Cuban-American freshman senator, he didn’t think he complemented Cruz particularly well. Lastly, Rubio felt that the nominee should have the freedom to pick whomever he or she wants at the convention to help win in November and not be bound to a short-term decision made in the thick of the primaries. The lack of bounce after Cruz attempted such a move with Carly Fiorina reinforced his belief that he was right, the source said.

A source close to Kasich reported that the Ohio governor tried to broach the subject with Rubio as well, and the campaigns discussed it as well, before and after the March 8 Michigan primary. Kasich’s team did not conduct any polling but they are also convinced if the two men had teamed up, “we would have swept the rest of the primaries.”

What the result would have been in these alternate universes where a Cruz-Rubio ticket was on the ballot, or a Kasich-Rubio team, is unknown. Trump, in this reality went on to win in Florida, Illinois, Missouri, North Carolina, and Arizona. He was not stopped.