Trump has hurt the Republican party with his behavior throughout the election. While generally I feel leaders should support their party, Trump is the exception. Blind loyalty to one party is damaging when you have someone like Trump who could do real damage in the White House. Paul Ryan has every right to criticize the ridiculous things Trump has done.
Paul Ryan, as a Republican and Speaker of the House, should most certainly be backing Donald Trump. Not only for the sake of party unity and the risk of looking like a fool after heading his convention, he should endorse Trump to help defeat Hillary Clinton who was a horrible First lady, lousy Senator, and disastrous Secretary of State and would be horrific as President. She would be mired in scandal and gridlock and probably face impeachment after her latest financial crimes are exposed.
Paul Ryan should criticize Donald Trump. It makes him look weak and foolish to support some of Trump's statements. These include those that are critical of a gold star mother and racist comments. Trump's refusal to endorse Ryan were childish and immature. The party and its leaders look ridiculous by blindly supporting Trump.
House Speaker Paul Ryan has a right to criticize Donald Trump. If Ryan finds criticism with something that Trump says, then Ryan has the right to speak out against it. Furthermore, Ryan represents the Republican Party to many that might be offended by Trump's bombastic remarks. Therefore, Ryan has a duty to call out Trump when the billionaire says something offensive.