DES MOINES — As a chance to evaluate possible 2016 Republican presidential candidates, the Freedom Summit here in Des Moines was a solid success. Several potential candidates — Scott Walker, Ted Cruz, Chris Christie, and a few others — left the 10-hour political marathon with their prospects undeniably enhanced.

All that was good news for Republicans. But at the same time, more than a few GOP loyalists came away shaking their heads at the performance of a party star, former vice presidential candidate Sarah Palin, whose long, rambling, and at times barely coherent speech left some wondering what role she should play in Republican politics as the 2016 race begins in earnest.