The nation's foreclosure crisis rarely is mentioned by the presidential candidates, but it looms large as their campaigns grapple with finding evicted voters in swing states.

Organizers are discovering scores of vacated homes in key battlegrounds that contributed strong turnouts in the 2008 election. In the past four years, more than 3.7 million homes have been lost to foreclosure, according to market research firm CoreLogic.

And canvassers have been left with voter databases — an indispensable tool for getting out the vote — riddled with outdated addresses and phone numbers.

Since the housing crisis went full tilt in 2008, the same states continue to have the worst foreclosure markets, such as California, Florida, Arizona and Nevada.

Today, three of the eight states with the highest foreclosure rates are presidential battlegrounds: Florida, Ohio and Nevada. Candidate Barack Obama won these states in 2008, but voter frustrations about his economic policies have since led each state to elect Republican governors.

Both the Obama and Romney campaigns say they are working to locate displaced voters, but declined to discuss their methods.

Given months of polling showing that likely Republican voters are more engaged in the election, Democratic officials and strategists in both parties say the Obama campaign has the greater challenge of mobilizing its base.

African-Americans and Latinos, two groups whose turnout is critical to Obama's chances, have lost homes to foreclosure at disproportionately higher rates, according to the Center for Responsible Lending.

Here's a sampling of conditions in those three pivotal swing states:

Florida: Evictions Limit Door-Knocking In I-4 Corridor

Florida, with its 29 electoral votes, is the biggest prize. It also has had the most foreclosures behind California over the past four years. Currently, 1 in every 352 homes is in foreclosure proceedings, nearly double the national rate, according to market research firm RealtyTrac.

Central Florida, along the Interstate 4 corridor, is ground zero for troubled mortgages, as well as swing voters.

For instance, the Tampa area recorded the nation's highest increase, at 47 percent, in foreclosure activity in the first half of the year. Tampa and surrounding Hillsborough County voted for Obama in 2008, but elected a Republican governor and senator in 2010.

Republicans believe the shift demonstrates that their strategy of tying the slow recovery to Obama's policies is working.

"We have an aggressive and robust ground game to identify and turn out voters in the I-4 corridor and beyond, many of whom are these homeowners directly impacted by President Obama's failed leadership," says Jill Bader, a spokeswoman for the Florida Republican Party.

In Orange County, the foreclosure rate has reached 36 percent, particularly in some Orlando neighborhoods with large Latino populations that voted for Obama.

A southeast Orlando precinct that includes the Lake Frederica and Ventura Country Club communities has had 545 foreclosures completed in the past year, and another 925 homes are in process, RealtyTrac says. About 46 percent of the precinct's roughly 9,700 registered voters are Latino.

Evictions in the Orlando area have prompted Mi Familia Vota, which registers voters in states with large Latino populations, to delay the start of door-to-door canvassing and hold registration drives at high-traffic sites such as gas stations and supermarkets.

"The process takes a little longer ... because a lot of people who used to be in those residences aren't there anymore," says Jose Balasquide, the Florida director for Mi Familia Vota. "So we have to invest more time in cleaning the voter lists, and we're probably going to find a lot of discrepancies."

Ohio: Cleveland May Not Be Obama's Juggernaut Again

Ohio, one of the most reliable bellwethers, has voted for the winning candidate in every presidential election since 1964. The Romney campaign is targeting suburbs and smaller towns that lean toward Republican candidates, while the Obama campaign is trying to mobilize large metropolitan areas that delivered him the state in 2008.

Obama supporters are finding the task more difficult this year in Ohio's two largest cities, Columbus and Cleveland, where foreclosures are highest. In the first half of the year, more than 10,717 properties, or 1 in every 89 homes, were in foreclosure in Cleveland.

Most of the properties are on the city's heavily Democratic east side, where thousands of homes bear an "X," marked for demolition.

"You see it in every precinct," says Samara Knight, vice president of the Service Employees International Union in Cleveland, who is leading a voter canvassing effort. The SEIU has endorsed Obama.

Since 2008, more than 99,000 of Cleveland's registered voters have dropped off the rolls, a loss of 26 percent.

"If they have moved and haven't voted since 2008, then it's really impossible to find them. Then I have lost that person," Knight says.

Nevada: 'Ghost Towns' Set Back Voter Registration

Nevada had the nation's highest foreclosure rate for much of the past five years until it dropped to sixth in July, RealtyTrac says. Nevada also had 12 percent unemployment in July, the highest of any state.

The conditions have prompted residents to leave the state, complicating voter outreach. A scrubbing of the state voter list in April removed some 64,000 registered Democrats who have departed Nevada. By comparison, Democratic voters outnumbered Republicans by nearly 100,000 when Obama won Nevada in 2008.

During a nonpartisan registration drive in Las Vegas last month, one SEIU official described visiting neighborhoods where "whole blocks are almost ghost towns."

Since April, Democratic voter registrations have increased by a 2-to-1 margin over Republican registrations, which also have been outpaced by nonpartisans, who choose no party affiliation.

"Nevada has always been a highly transient state, so re-registration is very important," says Rebecca Lambe, a senior adviser for the Obama campaign in Nevada.

Last year, Republican presidential candidate Mitt Romney angered some Nevadans when he said he opposed foreclosure relief for homeowners and preferred the market to "hit the bottom" so that investors could lead the recovery. A new Obama campaign radio ad airing in Nevada uses those remarks to attack Romney.

Romney last week told a Reno television station: "My plan for housing gets this market to come back. The president's plan for housing, now 3 1/2 years running, has not done the job." When asked, Romney didn't offer specifics about his plan.

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