Republicans set sights on Obama’s home state

Republican White House hopefuls have set their sights on President Barack Obama’s home state of Illinois in the hope of shaking up the plodding race to become their party’s standard-bearer.

Polls showed former senator Rick Santorum within striking range of frontrunner Mitt Romney, who has a commanding lead in all-important delegates but has been weakened by his failure to clinch the nomination.

The fierce Republican campaign was being waged as Obama was home in Illinois raising funds and waging his own offensive against the candidates.