Sept. 18 (Bloomberg) -- Barack Obama has spent tens of millions of dollars on advertising, consultants and polling.

It may be the money that he is spending on a database, though, that helps determine whether the Democrat wins the race for the White House this year. And he may have one of Hillary Clinton's top supporters, Harold Ickes, to thank for it.

George W. Bush won the last two presidential elections by targeting a small number of voters in just a few states. Obama is trying to ensure that doesn't happen again.

Ickes, a Democratic media consultant and former Clinton adviser, has spent four years and $15 million building Catalist, a database that scores 200 million Americans according to their likelihood to vote for party candidates. Illinois Senator Obama, 47, is one of his biggest clients.

``We have lost because we did not have the technical capability of finding voters that we needed to find and get them out to vote,'' Ickes said.

The model is VoterVault, a 12-year-old store of voter information that gave Republicans the edge in 2000 and 2004. In 2000, Bush lost the popular vote, though he carried the election by winning Florida by a margin of 537 votes out of more than 5.8 million cast. The 2004 race was equally close, with Iowa, New Mexico and even Ohio decided by less than 1 percent of the vote.

Tight Race

This year, with polls again showing a tight presidential campaign, Catalist may enable Democrats to level the playing field by allowing Obama and the party's down-ticket candidates to focus on voters who will support them and ignore those who won't, he said.

Catalist collects and stores millions of pieces of information from public records and commercial sources. In addition to voting rolls and tax information, it also has data about voters' magazine subscriptions and their cars. Campaigns also contribute e-mails, cell-phone numbers and even times when people are likely to be home.

Ickes, 69, said that by using Catalist the Obama campaign is able to generate data as detailed as lists of swing voters who are home in the afternoon in a six-block neighborhood in Cleveland, Ohio. The list can even suggest which voters would be receptive to a pitch based on Obama's ``change'' theme, and which may be more interested in his health-care or energy policies.

Greater Percentage

``Not every one is going to pan out, but a relatively high percentage is going to pan out compared to just going in to a geographic area and knocking on every door and phoning every home,'' Ickes said.

The database is also used by non-presidential candidates such as former Virginia Governor Mark Warner, now running for the U.S. Senate. In 2006, Ted Strickland used it in his successful run for governor in Ohio. Political consultants around the U.S. are also tapping into the database to help with state and local races.

VoterVault is owned and operated by the Republican National Committee while Catalist is a for-profit private enterprise.

That distinction allows Catalist to work directly with like- minded third-party groups such as the League of Conservation Voters or Planned Parenthood. VoterVault is barred by campaign- finance laws from working directly with Republican-leaning groups such as the National Rifle Association.

`For-Profit Company'

``That's why we created Catalist as a for-profit company,'' Ickes said. ``For our side, it's very big.''

At Catalist's headquarters in Washington, Chief Executive Officer Laura Quinn has a white board covered with the names of 80 progressive groups that share data with her company. Collectively, those groups represent approximately 25 million people.

Amber Wilkerson, a spokeswoman for the Republican National Committee, said VoterVault has an advantage over Catalist: ``We've been doing it a lot longer.'' She also said the database can update information on millions of supporters through state Republican groups.

Both VoterVault and Catalist have the same basic information, though the Democratic database can trade information with groups such as the Sierra Club, which has 1.3 million members and supporters. In addition, a dozen Democratic pollsters including Peter D. Hart Research Associates and Greenberg Quinlan Rosner are contributing the raw data from their polls to the Catalist.

Sierra Club

In 2006, the Sierra Club used Catalist to gather information about its own membership. Catalist developed a model of the typical member and used that data to generate a list of people with similar profiles who hadn't joined.

``Catalist helped us identify those people all across the country,'' said Cathy Duvall, the Sierra Club's political director. About 45 percent of the people contacted by Sierra Club from the list went on to write a letter or make a phone call in support of a candidate, she said.

Quinn said Catalist is using the data provided by the Sierra Club and other groups to target millions of potential Democratic supporters.

``A good database gives you a good model and then we can find you,'' Quinn said.

Ickes said the database may make the difference in November by identifying ``the right group of people and enough of them to make sure we win the Ohios and Michigans and Pennsylvanias.''

To contact the reporter on this story: Christopher Stern in Washington at cstern3@bloomberg.net.

Last Updated: September 18, 2008 00:01 EDT