Washington - With only 18 days left before presidential elections, the US Supreme Court Friday ruled against a voter registration request by Ohio Republicans that could have limited participation by newly registered, mostly Democratic, voters.

The challenge mounted in Ohio was among nationwide protests being filed by Republicans in key battleground states where Democratic nominee Barack Obama has put Republican John McCain on the defensive on normally Republican turf.

Washington - With only 19 days left before presidential elections, Republicans are mounting challenges to voter registrations in key battleground states such as Ohio, where election officials have asked the US Supreme Court to intervene.

The challenges mostly involve newly registered voters, and would likely hurt Democratic nominee Barack Obama, whose campaign has worked to register huge numbers of new voters around the country.