A commission reviewing proposed closures of U.S. military bases today rejected the Pentagon's recommendation to shut down Ellsworth Air Force Base in South Dakota, handing a political victory to a freshman Republican senator who had cited his clout with the Bush administration in unseating the Senate's top Democrat last year.

The commission later also rebuffed the Pentagon's plan to close Cannon Air Force Base in New Mexico, but it accepted a proposal to distribute the base's aircraft to other facilities. Under the compromise, Cannon would stay open until December 2009, an outcome that New Mexico's Democratic governor, Bill Richardson, described as a "partial victory."

The nine-member Defense Base Closure and Realignment Commission, known as BRAC, voted 8-1 to keep Ellsworth open, accepting arguments that savings projected by the Pentagon would not be realized, national security would be adversely affected and the economic impact on the Rapid City, S.D., area would be too great, among other factors.

The base on a stretch of prairie near Rapid City is home to 29 B-1B bombers, half the nation's fleet, and the Defense Department wanted to move them to Dyess Air Force Base in Texas to consolidate the B-1Bs in one place.

Sen. John Thune (R-S.D.), who upset the Senate's then-minority leader, Thomas A. Daschle, in last November's election, said after the commission's vote that the decision to keep Ellsworth open was made on the merits and was not political. Thune had sought to counter Daschle's Senate seniority during the election campaign by arguing that his own pull with the Republican administration of President Bush would be at least as important in preventing any move to close Ellsworth.

It came as something of an embarrassment to Thune when Defense Secretary Donald H. Rumsfeld on May 13 issued recommendations that included the closure of Ellsworth as part of a plan to save nearly $50 billion over the next two decades. The Pentagon recommended closing 33 major bases and reducing personnel at 29 others.

In the BRAC panel's votes since convening Wednesday, the commissioners have largely endorsed Rumsfeld's recommendations. Yesterday, they voted in favor of his plan to close Walter Reed Army Medical Center in Washington and move more than 20,000 defense jobs from leased office space in Northern Virginia to military bases. But the panel has refused to go along on a few major recommendations, voting to keep open two Navy bases in the Northeast and two Army depots in Texas and Nevada, as well as the Ellsworth and Cannon air bases.

Under the law, the commission must send its final report to President Bush by Sept. 8, and he can accept the whole plan or return it to the panel for revisions, but cannot make piecemeal changes. This also applies to Congress, which must accept or reject the plan in its entirety.

Standing with two Democratic lawmakers from South Dakota and the state's Republican governor, Thune, 45, said after today's vote that intensive lobbying to keep Ellsworth was a bipartisan effort.

"This is a great day for South Dakota, but we think it's a great day for America," Thune told reporters. He said the base-closing commission recognized Ellsworth's "importance in the war on terror," and he hailed the "open-mindedness" and "independence" of the commission members.

"I spent more time with the BRAC commission than I spent with my wife and family in the last three months," said Thune, who is considered one of the GOP's rising stars.

Asked if he felt politically strengthened, given his campaign arguments against Daschle, Thune said, "This fight was not about me. . . . Politics had nothing to do with this." He said that "in the end, what made this argument succeed was the merits." People "can do all the theorizing they want to do about politics," he said, but "the decision was on the merits."

Pressed on whether he felt he had made good on pledges to constituents during the campaign, Thune said, "At the end of the day, this was a process that was insulated from politics."

His statements were seconded by Sen. Tim Johnson and Rep. Stephanie Herseth, both South Dakota Democrats, and by Republican Gov. Michael Rounds.

"This is a great decision for America's national security," Johnson said.

Herseth said she was particularly pleased to hear that the commission recognized the impact on the community of closing Ellsworth.

"This was a team effort," Rounds said of South Dakota's lobbying campaign. "This was bipartisan in nature."

Since it was created during World War II, Ellsworth has been used to train B-17 bomber crews, become a home base for B-52 bombers and controlled an arsenal of intercontinental nuclear missiles hidden in underground silos. The missiles were deactivated in the early 1990s a few years after Ellsworth began receiving its B-1B bombers.

The motion to strike the Pentagon's recommendation to close Ellsworth was made by commission member Samuel K. Skinner, who served as transportation secretary and White House chief of staff during the administration of President George H.W. Bush. The commission is chaired by Anthony J. Principi, who served as secretary of veterans affairs during the first four years of the current Bush administration.

Ellsworth stood to lose 3,852 military and civilian jobs from the closure, according to a Pentagon assessment. But community leaders in Rapid City argued that the impact would be much greater, with about 11,000 people in the area -- 10 percent of the local work force -- losing their jobs. The base is the third-largest employer in sparsely populated South Dakota, after the state government and a private health care system.

The commission's staff also disputed the Pentagon's view that closing the base would save $1.85 billion over 20 years.

Another factor raised by opponents of the closure was a lawsuit by residents near Dyess Air Force Base that threatens to limit the opportunities for B-1B training that the Pentagon had wanted to consolidate.

In reaching a compromise on Cannon Air Force Base, home to 61 F-16s in the 27th Fighter Wing, the commission took account of concerns that closing the facility as recommended by the Pentagon would ruin the economy of nearby Clovis, N.M., near the border with Texas. The vote to keep the base open until 2009 but move the fighter wing was 6-1.

The more immediate closure recommended by the Pentagon would have eliminated nearly 4,800 jobs at the base and in the community.

Principi said closing Cannon was "very painful but also necessary."