By Alex Knott, CQ Staff

Unions, political action committees and other special interests shelled out nearly $98 million in independent expenditures to affect the presidential election, according to a CQ MoneyLine analysis of Federal Election Commission reports through Nov. 4.

While there was no “Swift Boat” ad that defined this year’s White House race, these special interest groups created a strong presence by spending almost twice as much as the national party committees on independent ads, canvassing and other campaign activities.

These groups overwhelmingly favored Democratic presidential nominee Barack Obama , spending $48 million in his behalf since June, while Republican nominee John McCain was promoted with $28 million over the same period. Another $22 million was spent during the primaries on behalf of all presidential contenders.

One reason outside organizations dominated the national parties in independent spending was because the Democratic National Committee decided to go a different route. The DNC chose to funnel more than $68 million directly to state parties and other party affiliates during the campaign and spent only $1.1 million on independent activities of their own.

The Republican National Committee, however, transferred far less to its state affiliates and instead spent $53.3 million on independent endeavors — much of it on a late advertising blitz against Obama just a few days before election day.

Leading the independent expenditure category for outside groups was the Service Employees International Union. It spent more than $28 million, a lot of it going to fund multi-lingual, 30-second spots promoting Obama and railing against McCain’s views on economic issues.

Other unions, including the United Auto Workers and the American Federation of State County & Municipal Employees, also took a decidedly pro-Democratic stand by favoring Obama over McCain with big expenditures.

Even though outside groups overshadowed the national parties in the race for the White House, they played a much smaller role in congressional races, where the party organizations dominated on independent spending. Still, these interest groups ended up targeting $41 million at 258 House and Senate races.

Among the groups that rung up the most in independent expenditures during the presidential election, were the following ten:

• Service Employees International Union, $28,672,962

• National Rifle Association of America, $6,890,820

• The National Republican Trust PAC, $6,592,925

• MoveOn.Org, $5,369,254