The two men's presidential hopes rest on appeals to the right-wing grassroots—and those voters seem to prefer Cruz. MANCHESTER, N.H.—Rand Paul has been methodically planning his run for president. Now Ted Cruz could come along and spoil the whole thing. Both senators have a path to the Republican nomination that rests on the support of the Tea Party. And when forced to choose, that segment appears to prefer Cruz, whose speech to an activists' gathering here over the weekend was the more enthusiastically received of the two. Saturday's Freedom Summit, billed as an early audition for potential 2016 candidates,...