Sen. Lincoln D. Chafee, a moderate who has frequently clashed with the Bush administration, beat back a strong conservative challenger Tuesday night in the GOP primary in Rhode Island.

The victory came amid heavy turnout, after the same Republican establishment that Chafee has so often defied rallied to his side with money and logistical support for a vigorous get-out-the-vote effort. While there is little personal affection for Chafee at the White House, operatives there and in the Republican Party leadership calculated that he is the GOP's best chance of holding the seat in a Democratic-leaning state in November.

The Chafee win represented a rare bit of political good news for Republicans, who are struggling to retain control of both houses of Congress in a highly volatile election year, as polls showing voters to be increasingly frustrated with GOP leadership. President Bush's dismal approval ratings, fueled in large part by public frustration with the war in Iraq , threatens Republican incumbents around the country who are on the ballot this year.

Stephen Laffey, the blustery, populist mayor of Cranston , had sought to become the second challenger to topple a senator in a primary this year, after Sen. Joseph I. Lieberman's loss to Ned Lamont in Connecticut 's Democratic primary last month. In the end, however, a race that for weeks had been widely viewed as neck and neck fell decisively in line for Chafee, who was commanding 54 percent of the vote with 99 percent of returns counted.

Chafee's hurdles are hardly over. Democrat Sheldon Whitehouse, who like Chafee is a well-known Rhode Island political figure, also secured his party's nomination Tuesday night over negligible opposition. Whitehouse was not a top choice of Democratic Party recruiters,but has led Chafee in recent polls.

Although Chafee escaped the Laffey threat, Democrats believe he compromised his general election chances by waging a negative campaign marked by pointed attack ads and by accepting such high-profile Republican Party help. The senator himself expressed regret last week that the tone of the campagn had turned nasty. But, he pointed out, "negative ads do work."

But they also clash with his low-key, almost diffident personal style and expressed loathing of glovers-off partisanship. "When Lincoln Chafee -- an incumbent Republican senator -- can barely win his own primary, you know he'll have trouble in the general election," said Sen. Chuck Schumer (N.Y.), chairman of the Senate Democrats' campaign committee.

National GOP officials feared that if Chafee lost, Democrats would almost certainly win the Senate seat in November, one of six they must pick up to reclaim control of the chamber. National Republican officials who are backing Chafee announced last week that they would pull their resources out of Rhode Island should Laffey prevail, effectively conceding the election to Democrats.

"This is my 10th run for office . . . and I've never had one like this," said Chafee, the son of the late senator John H. Chafee and a former Warwick mayor and City Council member. He said the vote was an endorsement of the "spirit of compromise" that he has tried to uphold. Then he reminded supporters that a whole new battle is beginning. "It will take everything we've got," Chafee said.

Rhode Island was one of nine states that held primaries Tuesday, the last big day of party battles before the November elections. The GOP faced a similar intraparty conflict in Arizona in the contest to succeed retiring Rep. Jim Kolbe (R), a longtime member of the House Appropriations Committee. Republicans chose between Randy Graf, a conservative firebrand running hard against illegal immigration, and state Rep. Steve Huffman, a moderate who was backed by Kolbe and the national party.

In New Hampshire , Democrats who oppose the Iraq war showed their strength again, just as they had in the Lieberman-Lamont election. In the 1st Congressional District, Carol Shea-Porter stressed antiwar themes in her upset victory over party-backed Jim Craig in the contest to take on Rep. Jeb Bradley (R).

Meanwhile, Arizona state Sen. Gabrielle Giffords and former Tucson anchorwoman Patty Weiss battled for the Democratic nomination. Democratic officials say they are confident that if Graf wins the GOP primary, either Giffords or Weiss could beat him in November in the race for the swing seat.

But the contest in Rhode Island has the most potential to change the political map. With control of the Senate seat at stake, the national Republican Party recently began a series of television commercials and mobilized its get-out-the-vote effort in a bid to save Chafee from defeat. The maverick senator has opposed President Bush on many issues and voted against the president in 2004.

But the national party rallied behind Chafee, nonetheless, convinced that Laffey was too conservative to win in the heavily Democratic state. A huge final-hour turnout effort appeared to have paid off, with over 63,000 ballots cast, by far a state record for a GOP primary.

In contrast to Chafee's patrician and somewhat diffident style, Laffey was assertive and hard-charging, and he proved highly effective on the campaign trail. He argued that Chafee's independence from the GOP has made him almost irrelevant and that his unpredictable voting patterns suggest a political identity crisis.

The race turned ugly in the final days, with accusations of dirty tricks, and the harshest attacks aimed at Laffey. The intense atmosphere was highly unusual in a state that barely rates on the national political radar. Voters reported receiving a dozen pieces of mail in one day and their phones ringing 15 times in 10 minutes, all political pitches.

Laffey's strong campaign suggested a worrisome trend to Republicans about their base supporters: that intolerance for moderates had grown so intense that they were willing to sacrifice a Senate seat -- and possibly control of the Senate -- to punish unreliable politicians.

The mayor's core supporters were Republicans who disliked Chafee's moderate views, but he also also appealed to middle-class independent voters who are uneasy about Congress's inattention to issues they care about, such as education and health care. Those voters think only an outsider can shake up Washington , and in Laffey's case, they were willing to overlook ideological differences.

"I ran as a reformer," Laffey told supporters Tuesday night, conceding the race and endorsing Chafee. "We take ideas any day."

Meanwhile, in Minnesota , Democrats chose state Rep. Keith Ellison from a field of four main candidates for a Minneapolis House seat being vacated by retiring Rep. Martin O. Sabo (D). In a heavily Democratic district, he is on track to become the first Muslim to serve in Congress.

In New York , Sen. Hillary Rodham Clinton (D) was nominated for a second term, while Attorney General Eliot L. Spitzer won victory as the Democratic nominee for governor.

In a majority-black district in Brooklyn , City Council member David Yassky, the only white candidate in a four-way contest that raised racial tensions, lost to Yvette Clarke in the Democratic primary to replace retiring Rep. Major R. Owens.