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: West Des Moines, Iowa (CNN) Donald Trump had every reason to feel optimistic Monday. His poll numbers were up; he had secured two prominent endorsements in the space of a week; and even the weather seemed to be cooperating, with a snowstorm coming in from the west expected to hold off until after midnight. Sarah Palin endorses Donald Trump And then, he lost, coming in second to Ted Cruz. Trump spent January in full-on attack mode against Cruz. Trump questioned whether Cruz qualifies as a "natural-born citizen" eligible to serve as president. He went after the evangelical vote, winning the endorsement of Liberty University President Jerry Falwell, Jr., but didn't back up the appeals with a ground game. And then he sat out the final debate, opting for a rally across town at the same time.Donald Trump finished second in the Iowa caucuses on Monday nightHe sat out the final debate in Iowa and he acknowledged Tuesday that his plan might have backfired 
 Question:With _'s win and Marco Rubio's much stronger-than-expected finish Monday night, Trump now urgently confronts the danger of the Florida senator chipping away at his establishment backing in upcoming contests.

Ted Cruz