"Some other recent conventions have had several lawmakers who notably skipped their party's nominating event. In 2008, many vulnerable GOP senators didn't attend in a year where outgoing President George W. Bush's approval rating was abysmal. In 2012, many moderate Democrats also skipped out on President Obama's convention.
"But never before in recent history have so many prominent party officials boycotted the event or found convenient other reasons not to attend because they either didn't approve of or were uncomfortable with their party's presumptive nominee."
Jessica Taylor at NPR reports on Republican no-shows at the party's convention.