FACTBOX: Ohio and its presidential primary

(Reuters) - The Midwestern industrial state of Ohio will host a crucial showdown between Democratic presidential candidates Barack Obama and Hillary Clinton when it holds its primary contest on Tuesday.

Following are a few facts about the Buckeye State:

* Ohio is considered a "must win" state for Clinton if she is to prevent Obama from becoming the Democratic nominee. Republican front-runner John McCain hopes to move closer toward clinching his party's nomination.

* White working-class voters make up a large share of Ohio's electorate and Clinton has done well with these voters in many other state contests, although Obama has begun to win them over. Recent public opinion polls show Clinton leading Obama by an average of 10 percentage points in Ohio.

* Pocketbook issues top voters' concerns in Ohio. The state has lost 23 percent of its manufacturing jobs since 2000 and the subprime mortgage crisis has hit hard, with foreclosures climbing 88 percent in 2007. Cleveland is the nation's poorest large city, where nearly half the children live in poverty.

* Polls open at 6:30 a.m. (1130 GMT) and close at 7:30 p.m. EST (0030 GMT). Both the Republican and Democratic contests are open to independent voters.

* Ohio has been a swing state in presidential races, narrowly handing President George W. Bush a re-election victory in 2004. Democrats in 2006 picked up a number of statewide offices, including the governor's mansion and a U.S. Senate seat, after scandals hurt incumbent Republicans.

Sources: Ohio Secretary of State; Alliance for American Manufacturing; Real Clear Politics; RealtyTrac; Almanac of American Politics

(Reporting by Andy Sullivan in Washington, editing by Vicki Allen)