Republicans are hatching a political comeback by dusting off a strategic playbook written nearly two decades ago. Its themes: Unite against Democrats’ economic policy, block and counter health care reform and tar them with spending scandals. Those represent the political trifecta that former House Speaker Newt Gingrich bet on in 1994 to produce a historic Republican takeover of Congress. Now, some Republicans believe President Barack Obama’s one-two push on the economy and health care reform is setting the stage for a new round of significant gains, if not a total takeover. “There are two models that Republicans are looking at,”...