WASHINGTON — Republican Sen. Gordon Smith has spent more than $10 million as he seeks to defend his seat in Oregon’s closely watched Senate race.

New campaign finance reports show Smith spent more than $4.8 million in the three months that ended Sept. 30. That brings his total spending for the campaign to nearly $10.1 million, according to a report filed Wednesday with the Federal Election Commission.

Smith’s Democratic opponent, Oregon House Speaker Jeff Merkley, has spent about $4.1 million so far, including about $1.9 million in the three months that ended in September.

The escalating spending totals — visible to any Oregonian who watches TV — underscore the high stakes of the Senate race, which most observers consider a toss-up.

The fundraising totals do not include millions of dollars sent by outside groups, such as the Senate campaign committees of both parties, as well as business and labor groups and other special interests.

Merkley’s campaign Wednesday complained that one of the outside groups, the Republican-leading Freedom’s Watch, is running anti-Merkley ads that are “strikingly similar” to ads run on behalf of President Bush in 2004. Freedom’s Watch was launched by former White House officials and donors friendly to the president.

Karl Rove, a former top Bush aide, is a key adviser to Freedom’s Watch, and Merkley complained at a debate this week that Rove is behind a $2 million “smear campaign” against him.

Smith shot back that Rove has nothing to do with his campaign.

In a letter to Smith’s campaign, Merkley’s campaign manager, Jon Isaacs, said Rove is “intimately involved” in the Senate race. He cited an ad by Freedom’s Watch attacking Merkley for supporting higher taxes — a charge Merkley denies.

Isaacs urged Smith to demand that Rove and Freedom’s Watch halt all campaign attacks on Smith’s behalf.

Lindsay Gilbride, a spokeswoman for Smith, dismissed the Democratic allegation out of hand.

“To even insinuate that Karl Rove is working on behalf of the Smith campaign is disingenuous and laughable,” she said.

Smith would prefer that no out-of-state money is spent on the race, Gilbride said. “However, Jeff Merkley, from the first day of this campaign, has been exclusively propped up by out-of-state money from special interests and the national (Democratic) party.”

The Democratic Senatorial Campaign Committee, labor unions and other groups, including the Majority Action Fund, a liberal advocacy group, have spent at least $11 million helping Merkley and attacking Smith, Gilbride said. Much of that money was spent during the Democratic primary campaign, when Merkley defeated Portland lawyer Steve Novick to win the party’s nomination.

“Jeff Merkley’s campaign would not be alive today were it not for out-of-state special interest money,” Gilbride said. “They’ve paid for everything from his trash bill to his TV ads.”

Merkley’s spokesman, Matt Canter, said Smith and his GOP allies are likely to outspend Merkley and Democratic groups by a 2-to-1 margin.

“He’s the incumbent who sits on the Senate Finance Committee, and he has shaken down special interests to amass an enormous war chest,” Canter said, citing contributions from the oil industry, pharmaceutical groups and the financial services industry.

Even so, Merkley has outraised Smith in each of the last two quarters, Canter said.

In his report, Smith said he raised about $1.9 million in the previous quarter, bringing his total for the campaign to $11.6 million.

Merkley reported raising $2.1 million this quarter for a total of $4.9 million.

Smith reported $1.5 million cash on hand to $766,200 for Merkley.

Both national parties have targeted the Oregon race. The DSCC and its Republican counterpart, the National Republican Senatorial Committee, each reported spending more than $5 million in independent expenditures in Oregon, according to a report filed with the FEC.