Arizona Gov. Doug Ducey has already helped block one of former President Donald Trump’s allies from winning the Republican nomination for governor in a crucial battleground state. Now he’s hoping for a repeat in his own backyard. Ducey is part of a burgeoning effort among establishment Republicans to lift up little-known housing developer Karrin Taylor Robson against former television news anchor Kari Lake, who is backed by Trump. Other prominent Republicans, including former New Jersey Gov. Chris Christie, have also lined up behind Robson in recent days. On Monday, Robson’s campaign announced the endorsement of former Vice President Mike Pence,...