Democrats have tried improving the political climate, discrediting their Republican opponents and asking Americans for patience in tackling the nation's challenges, but the party's best hope of stemming deep losses on Election Day may now rest on loyalty and logistics, not persuasion. The final seven days of the campaign provide the biggest test yet for the enduring strength of President Barack Obama's network of supporters, which party leaders are relying on to build a critical firewall in races for Congress and governor. Republicans hold an array of advantages with the electorate, but Democrats believe their voter turnout operation is one key equalizer. As Republican candidates and their allies rely more on television advertising to rally their core voters, Democrats are deploying a presidential-style effort to awaken supporters and ensure they cast a ballot. The get-out-the-vote program by Democrats and their allies will not save all of their endangered candidates, but organizers hope it can help offset excitement among Republican voters, particularly in Ohio, where early voting has been under way since Sept. 28. For all the talk about how Obama has been an anchor on Democratic candidates -- Rep. Gene Taylor of Mississippi, locked in the toughest race of his career, declared over the weekend that he voted for Sen. John McCain for president -- there are other places where the president is seen as the last best hope of salvaging his party's majority or helping Democrats like Gov. Ted Strickland of Ohio win re-election. The president is visiting Cleveland on Sunday -- his second trip in two weeks -- for a rally at the Wolstein Center at Cleveland State University. The site was picked for a reason: The Cuyahoga County Board of Elections office is less than a half mile away, and the Ohio Democratic Party will offer rides for people to cast early ballots. Organizing for America, the network that grew out of Obama's campaign, began a program this week intended to reach 7 million voters over seven days. The president will speak on a conference call to thousands of volunteers from the group on Wednesday evening, an incentive for people to hear directly from him and get them to agree to help Democratic candidates in the final push to Election Day. 'For the 2008 first-time voters, specifically, they really wanted to change the country,' said Jeremy Bird, deputy director of Organizing for America. 'When folks see the president, it really makes them think about the importance of continuing that change. We want folks to really recognize the importance of the midterm elections and make the case for how important these elections are for the future.' 