Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: Washington (CNN) Top Republicans are becoming nervous that they may lose Marco Rubio's Senate seat and their tenuous majority in the chamber -- and now many want the Florida senator to reconsider his decision to leave office. Behind the scenes, a number of senators, donors and leading party officials have privately prodded Rubio to make a late entry into the race to prevent his seat from flipping, several sources told CNN. Rubio is declining -- but the pressure is only bound to intensify ahead of the June 24 filing deadline, with everyone from Donald Trump to freshmen lawmakers lending their voice.On Thursday, Sen. John Cornyn became the highest-ranking GOP official to publicly call for Rubio to run for re-electionRepublicans believe that the candidate favored by the Democratic establishment is flawed and can be beaten 
 Question:In a Tuesday interview with CNN, _ said that his "really good friend" of 25 years -- Lopez-Cantera -- is likely to win his endorsement.

Marco Rubio