LOUISVILLE, Ky. — Barack Obama stepped to the brink of victory in the Democratic presidential race Tuesday night, defeating Hillary Rodham Clinton in the Oregon primary and moving within 100 delegates of the total he needs to claim the prize at the party convention this summer.

"You have put us within reach of the Democratic nomination," he told cheering supporters in Iowa, the overwhelmingly white state that launched him, a black, first-term senator from Illinois, on his improbable path to victory last January.

Obama lavished praise on Clinton, his rival in a race unlike any other, and accused Republican John McCain of a campaign run by lobbyists.

"You are Democrats who are tired of being divided, Republicans who no longer recognize the party that runs Washington, independents who are hungry for change," he said, speaking to a crowd on the grounds of the Iowa Capitol in Des Moines as well as the millions around the country who will elect the nation's 44th president in November.

Clinton countered with a lopsided win in Kentucky, a victory with scant political value in a race moving inexorably in Obama's direction.

The former first lady vowed to remain in the race, telling supporters, "I'm more than determined than ever to see that every vote is cast and every ballot is counted."

But in a sign of confidence on the front-runner's part, party officials said discussions were under way to send Paul Tewes, a top Obama campaign aide, to the Democratic National Committee to oversee operations for the fall campaign.

And in a fresh indication that their race was coming to an end, Clinton and Obama praised one another and pledged a united party for the general election.

"While we continue to go toe-to-toe for this nomination, we do see eye-to-eye when it comes to uniting our party to elect a Democratic president this fall," said Clinton, whose supporters Obama will need if he is to end eight years of Republican rule in the White House.

Clinton won at least 54 delegates in the two states and Obama won at least 39, according to an analysis of election returns by The Associated Press. All the Kentucky delegates were awarded, but there were still 10 to be allocated in Oregon, and Obama was in line for many of them.

He had 1,956 delegates overall, out of 2026 needed for the nomination. Clinton had 1,776, according the latest tally by the AP.

Obama's total includes more than a majority of the delegates picked in the 56 primaries and caucuses on the calendar, a group that excludes nearly 800 superdelegates, the party leaders who hold the balance of power at the convention.

With about 50 percent of the votes counted in Oregon's unique mail-in primary, Obama was gaining a 58 percent share to 42 percent for Clinton.

The former first lady's victory in Kentucky was bigger yet — 65 percent to 30 percent — and the exit polls underscored once more the work Obama has ahead if he is to win over her voters.

Almost nine in 10 ballots were cast by whites, and the former first lady was winning their support overwhelmingly. She defeated him among voters of all age groups and incomes, the college educated and non-college educated, self-described liberals, moderates and conservatives.

"We have had our disagreements during this campaign, but we all admire her courage, her commitment and her perseverance," Obama said of Clinton. "No matter how this primary ends, Senator Clinton has shattered myths and broken barriers and changed the America in which my daughters and yours will come of age."

As for McCain, he said he would leave it up to the Arizona senator "to explain whether his policies and positions represent long-held convictions or Washington calculations, but the one thing they don't represent is change."

McCain's spokesman countered quickly.

"This election is fundamentally about who Americans can trust to secure peace and prosperity for the next generation of Americans. Without a doubt, Barack Obama is a talented political orator, but his naive plans for unconditional summits with rogue leaders and support for big tax hikes on hardworking families expose his bad judgment that Americans can ill-afford in our next president," said Tucker Bounds in a statement.

In the fundraising chase, Obama reported cash on hand of $46.5 million, all of which can be used for the general election. Unless he takes federal funds, he is permitted to raise as much as he can.

Unlike Obama, McCain is expected to take federal funds, which total about $85 million and bar him from raising other donations for his campaign's use.

"We still have work to do to in the remaining states, where we will compete for every delegate available," Obama said in an e-mail sent to supporters. "But tonight, I want to thank you for everything you have done to take us this far — farther than anyone predicted, expected or even believed possible."