WASHINGTON - Donald Trump is openly taunting the leaders of his own party by refusing to endorse House Speaker Paul Ryan of Wisconsin and Sen. John McCain of Arizona in their GOP primaries.

And so far, McCain, Ryan and other Republicans who've reluctantly declared that they plan to back Trump for president appear to be sticking with him.

Trump's stunning slap at two of the nation's most prominent Republicans dramatically escalated GOP turmoil barely a week after a convention intended to promote party unity.

With the general election campaign now squarely underway, Republicans found themselves once again forced to answer questions about the latest boundary-defying pronouncement from Trump at a moment when most would rather be talking about Hillary Clinton's record.