The Republican presidential primary field is shaping up to have about a dozen contenders in 2016, and U.S. Sen. Ted Cruz of Texas may become one of them. But if Cruz decides to mount a campaign, his biggest strength -- strong support among conservative, tea party voters – may also be his biggest liability. While he hasn’t yet officially announced a run for president, Cruz has said he is strongly considering it. In October, he made a visit to the Wichita, Kansas, headquarters of the oil billionaire Koch brothers to make the case that Republicans need a grassroots conservative as...