Maximising turnout key to winning in Ohio

After all the fundraising, political ads, rallies, meetings and get-out-the vote efforts, a few counties in just one state - Ohio - could have an outsized say in the outcome of the election.

At a national level polls showed President Barack Obama and Republican rival Mitt Romney tied. Under most calculations, Ohio with its 18 electoral college votes became the most critical battleground in the candidates' state-by-state race to capture the 270 electoral votes needed to win the White House.

A Reuters/Ipsos poll on Sunday showed Obama leading the former Massachusetts governor 48 per cent to 44 per cent in Ohio. Obama won the state by 4.6 percentage points in his defeat of Republican John McCain in 2008.

To win the state, the Obama team may have to maximise turnout in the north, particularly in Cuyahoga County around the industrial and manufacturing Democratic stronghold of Cleveland, an area that is home to roughly 10 per cent of the state's population. The northern part of the state is deeply tethered to the car industry and has a strong presence of organized labour.

Obama also needs to avoid losing badly in Hamilton County, which the Democrat won in 2008 but which typically leans Republican. Hamilton County is in the southwestern corner of the state, adjacent to Kentucky and includes the city of Cincinnati. It has many conservative voters - and is surrounded by some of the most Republican-friendly parts of Ohio, including House of Representatives Speaker John Boehner's 8th District. Obama is fighting for a draw there, said a Democrat with ties to the campaign. "But we can't lose by more than three to four points."

On the other hand the Romney campaign needs to maximise turnout in the suburban and rural areas, especially in the conservative southeast and in Hamilton County, and to eat into Obama's margin in the north. Romney likely needs to carry Hamilton County to have a shot at the state overall.