PORTLAND  — Despite his move to the political middle, two-term incumbent Republican Gordon Smith has lost his U.S. Senate seat to Democratic challenger Jeff Merkley.

It was the first time in 40 years that an incumbent senator from Oregon has been booted from office. Smith was the last GOP senator along the West Coast south of Alaska.

For Merkley, it was a remarkable personal victory. The state House speaker and policy wonk was far from the first choice of national Democrats looking for a challenger to Smith.

“There’s a lot of work for us to do together,” Merkley told a crowd of supporters Thursday morning as they jammed a room at Portland State University and spilled into the hallway.

“It’s time for a very different approach,” he said, in such areas as health care, job creation, affordable housing and energy independence.

He was with his fellow Democrat, Sen. Ron Wyden, who said it wasn’t an easy decision for Oregon to replace Smith.

Merkley, said Wyden, “is not just going to be a good Oregon senator, he’s going to be a great one.”

Smith gave a concession speech from his home in Pendleton.

“There was simply a tide too strong for us to stem. We understand that,” said Smith, his arm around his wife.

For Smith, the election represented a stinging rejection by voters of his political strategy. He ran TV ads touting his work with Barack Obama, Ted Kennedy and other prominent Democrats on issues such as alternative energy.

Merkley countered with a TV ad featuring Obama directly urging Oregonians to vote for Merkley. It was the only TV ad Obama had done for another candidate during the general election, showing the importance that national Democrats placed on the Oregon race.

A year ago, most observers doubted that Merkley could defeat the better-funded Smith, a millionaire owner of a frozen foods processing plant and former state legislative leader.

Merkley turned the race in his direction with millions of dollars in help from national Democrats and a campaign blitz that took him to 100 communities around the state.

Merkley is one member of a class of Democrats elected to the Senate in the election that put Obama in the White House.

So far, Democrats have at least 57 votes in the U.S. Senate with the outcome of three other races yet to be determined. A runoff election is to be held in Georgia, a re-count is scheduled in Minnesota, and the outcome in Alaska wasn’t clear.

A flood of votes Oregonians delivered on election day kept election workers tallying ballots for two days.

Merkley planned an appearance Thursday morning to claim victory, and Smith planned a press conference in the afternoon.

Lindsay Gilbride, a spokeswoman, said Smith called Merkley on Thursday morning to concede.

Before an appearance at the Hatfield School of Government at Portland State University, Merkley issued a statement saying he was “the first leader in 40 years to defeat an incumbent U.S. Senator in Oregon.”

Forty years ago this week, Republican Bob Packwood was declared the winner in an upset of Democratic Sen. Wayne Morse.

Early Thursday, about 82 percent of the vote had been counted statewide. Merkley had a margin of more than 40,000 votes.

His victory margin came from his home county — Multnomah. He represented an east Portland district.

The 52-year-old Merkley announced his candidacy for Senate in August 2007 after better-known Democrats declined to run.

In his campaign stops around the state, Merkley tapped into an anti-GOP tide in Oregon, telling crowds that Smith was a Bush Republican who was more interested in bailing out Wall Street than helping folks on Main Street.

Merkley and has wife, Mary Sorteberg, a registered nurse, have two children.