Between television ads, radio spots and mail flyers, U.S. Senate candidates Gordon Smith and Jeff Merkley are spending their way through a tight and sometimes nasty race.

Smith, the Republican incumbent, has spent nearly $9.7 million dollars in his bid to stay Oregon’s junior U.S. senator, while Democratic challenger Merkley has dished out about $5.3 million.

Together, the candidates have splurged just more than $15 million, according to the latest reports the campaigns filed with the Federal Election Commission.

That doesn’t include any of the money the Republican and Democratic Senate campaign committees have poured into the race – nor what businesses, unions or other special interest groups have spent.

The race has far outstripped Smith’s 2002 Senate race, in which Smith spent almost $7.4 million while his Democratic opponent, Oregon Secretary of State Bill Bradbury, spent about $2.1 million.

And the major contributors to each campaign reveal stark contrasts.

Some very big corporate names are among Smith’s major givers, while major unions and labor organizations are on Merkley’s donor list.

Smith’s No. 1 contributor is Marriott International. The global hotel conglomerate has given $59,800 to Smith’s campaign. Marriott International also was a major contributor to Smith’s 2002 run, giving $17,000 then.

But Smith, who was in Pendleton on Friday, said Marriott isn’t seeking any special favors. Instead, Smith said the Marriotts are long-time family friends.

Smith said he grew up with the Marriotts as neighbors in Maryland. And Bill Marriott, the company’s chairman and chief executive officer, is a member of the Church of Jesus Christ of Latter-day Saints, just as Smith is. Further, Marriott is Smith’s elder teacher in the church.

Merkley’s No. 1 contributor is ActBlue, a Web-based fundraising platform that funnels money from contributors to Democratic Party candidates. ActBlue has given Merkley’s campaign $116,068.

Merkley campaign spokesman Matt Cantor said Merkley has used ActBlue to organize significant grass roots support, in the same vein as Democratic presidential candidate Barack Obama.

Some of Smith’s other big donors include insurance giants Blue Cross/Blue Shield, MetLife and Northwestern Mutual. He also has received thousands of dollars from Intel Corporation, Nike and DaVita Inc., the nation’s second-largest dialysis provider with centers in Hermiston and on the Umatilla Indian Reservation near Pendleton.

Northwestern Mutual rounded out Smith’s Top 10, with a $25,100 contribution. Comparatively, Merkley’s No. 2 contributor has been Oregon state employees, who collectively have given $23,600.

After that, contribution amounts drop considerably, to the $12,000 mark or below, and many unions and political action committees tie for sixth place after each gave $10,000 to Merkley’s campaign.

The unions include the usual Democratic supporters – the AFL-CIO, the American Federation of State, County and Municipal Employees and Service Employees International Union.

The PACs include U.S. senator leadership fundraising arms, which members of Congress set up to support other candidates. The leadership PACs of Democratic Sens. Charles Schumer of New York, Patty Murray of Washington, Robert Menendez of New Jersey and Barbara Boxer of California each gave $10,000.

Merkley also received $10,00 from NARAL Pro-Choice America and Washington Women for Choice.

Additionally, two real estate companies are among Merkley’s top contributors: Rudin Management, a major New York firm, and Newmark Knight Frank, one the world’s largest privately-held commercial real estate firms.

Cantor said more than 25,000 contributors have given to the Merkley campaign, and he estimated more than 90 percent of those were contributions of under $100.

Democratic contributions for all races in Oregon this election cycle are outpacing Republican contributions. Democratic contributions have totaled more than $10.1 million, while Republican contributions are just short of $7 million.

In the last presidential election, Democrats took in $8.37 million and Republicans $8.33 million.

PAC donations this presidential election also are up. In 2003-2004 PACs gave nearly $438,000 while this election they topped $500,000.