If Sen. Marco Rubio had agreed to become Sen. Ted Cruz's running mate, the duo could have stopped Donald Trump from becoming the Republican nominee for president, Cruz officials told CNN.In the aftermath of Trump being left as the only remaining Republican candidate in the primaries this week, several officials in the Cruz campaign said the Texas senator offered Rubio the vice presidential spot in early March after their internal polls showed such a combined ticket would easily defeat the real estate mogul in several states which at that point had not yet voted.But those officials told CNN that Rubio was not interested in the idea. Officials in the Florida senator's campaign said there was never such a concrete offer. They added that in any case Rubio would have rejected it because such a ticket would be ineffective in defeating Trump, especially since both candidates are of Cuban heritage and as senators would have been viewed as being two insiders ganging up on an outsider, which would have played into Trump's storyline.Thecriticized the Cruz campaign for trying to deflect blame, pointing out that the Texas senator had insisted all along that he could challenge Trump if Rubio bowed out of the race, and so it was not fair now to start pointing figures when Cruz couldn't make good on his promise to beat Trump in such a scenario.However,, another conservative blog, said that such a combination would have at the very least prevented Trump from getting the delegates necessary to avoid a contested convention and a Cruz/Rubio combination would have stood a good chance of winning on a second ballot in Cleveland.But, the blog added, it was unrealistic for Cruz to have expected Rubio to give up his presidential bid at that stage of the race.