Mitt Romney’s double-barreled victory in the Arizona and Michigan primaries yesterday gave him a burst of momentum in the Republican presidential race as the contest shifts to Southern states and Ohio, where his appeal among evangelical and working class voters will be tested anew.

Two months into the voting and nine months into Romney’s second presidential run, the results confirmed his status as fragile front-runner, toiling to win over Republican voters as he heads into potentially pivotal Super Tuesday races March 6.