Want to make a political scientist's head explode? Explain to them how Donald Trump is a winner because he is leading polls and winning crowded primaries. In the back of their mind, the political scientist is thinking "he's 'winning' because the vote is fractured," and resisting the urge to say "the worst way to pick someone for office is to just take the person with the most votes, but not a majority."
Scenario one. President Sanders or Clinton, unlike President Obama on his first day on the job, are faced with a GOP controlled House and a GOP controlled Senate. Scenario two. Either President Trump, Cruz or Rubio, on their first day in office, faces a Democratic-controlled Senate. Senate Majority leader Mitch McConnell is determined to do everything to prevent scenario number one from happening. He is absolutely horrified at the thought of scenario number two happening.
Whatever misgivings he might have, Marco Rubio could not refuse an invitation from mayors of 12 Florida coastal communities to discuss their climate change concerns. Politics dictated that he meet with the mayors, several of whom are Republicans, to confer on a subject not as high on his agenda as on theirs.
Early this year President Obama spoke before the Cleveland Club. After the speech 7th grader Alura Winfrey inquired, "If you could go back to the first day of your first term what advice would you give yourself?" Obama reflected for a moment and then blithely explained he would have worked harder to sell his economic policies.