LOS ANGELES — For many of the Republican presidential candidates who expected to be at or near the top of the polls now, finding a solid base of support has proven to be a daunting challenge.

From candidates such as former Florida Gov. Jeb Bush to Wisconsin Gov. Scott Walker, New Jersey Gov. Chris Christie and Ohio Gov. John Kasich – all members of the governing Republican establishment and each twice elected statewide – the summertime success of Donald Trump has created unexpected obstacles.

Instead of moving forward, some of them have been going backward. That has left the party no closer to knowing who its 2016 nominee will be than it was when campaigning started many months ago. Instead the party is beset with questions.

Trump, who did not have a strong performance at the second Republican debate Wednesday in Simi Valley, has an obvious vulnerability. He must convince more voters that someone who is such a flamboyant entertainer and so enamored with himself can serve effectively as president.

His rivals remain hopeful that he will never pass that test and become the Republican nominee. But who among them is capable of winning enough hearts and minds to emerge as the eventual winner?

Presidential debates rarely prove to be game changers. Wednesday’s forum was no exception. There was a clear winner: Carly Fiorina, whose challenge will be to translate positive reviews into real support.

None of the other candidates earned the same kind of plaudits, but they felt like winners nonetheless, largely because they could say they saw signs of weakness in Trump’s candidacy. At different points in the three-hour debate, he looked deflated, groping on issues and hardly the center of attention.

But if his rivals hope he has hit a ceiling and or even begins to sag, they should not expect it to happen overnight. Trump has proven more resilient than they expected.

– The Washington Post