Moderate Republican Sen. Lincoln Chafee of Rhode Island, who bucked President Bush on tax cuts and the war in Iraq, defeated a conservative challenger Tuesday in a contest crucial to the larger fight for control of Congress.

With 99 percent of precincts reporting, Chafee had 34,042 votes, or 54 percent, to Cranston Mayor Steve Laffey's 29,431 votes, or 46 percent.

Chafee, whose challenge was the latest test of anti-incumbent sentiment and the polarization of politics, told supporters: "Our goal has always been to find the common ground for the common good. ... Partisan politics must not prevail."

Tuesday marked the last big day of primaries before the November elections, with races also in Arizona, Delaware, Maryland, Minnesota, New Hampshire, New York, Vermont, Wisconsin and the District of Columbia.

In New York, frontrunning Democrats swept aside primary challengers — Sen. Hillary Rodham Clinton trounced an anti-war candidate in her re-election bid, Attorney General Eliot Spitzer crushed his opposition for the Democratic nod for governor, and Andrew Cuomo easily won the party nomination for attorney general.

In Minnesota, state Rep. Keith Ellison won the Democratic nomination for an open House seat that could make him the first Muslim in Congress. In a reliably Democratic district that's voted close to 70 percent for the Democrat for nearly 30 years, he's likely the fall winner, too.

In Rhode Island, the importance of holding onto a GOP Senate seat brought Laura Bush and the GOP establishment to campaign for Chafee — even though he was the only Republican to vote against the resolution to use force against Iraq and he opposed the president's tax cuts. Chafee did not even vote for Bush in 2004 — instead writing in the name of Bush's father, former President George H.W. Bush.

Polls show Chafee will still face a tough contest against Democratic nominee Sheldon Whitehouse, a former attorney general. But if Chafee had lost, polls showed Whitehouse was almost assured a victory. Democrats hope to build on national dismay with Bush to capture majorities in Congress, and they need six Senate seats.

Chafee, 53, was appointed to the Senate in 1999 after his father, Sen. John Chafee, died in office. He won election the following year. Like his father, Chafee is an economic conservative and social moderate — a classic New England Republican whose more liberal views have drawn support from unaffiliated voters and some Democrats.

Rhode Island allows voters who are not registered with a party to cast ballots in either Republican or Democratic primaries, and on Tuesday, many of them gravitated toward Chafee.

An ecstatic Chafee pumped his arms in the air and emphasized his ability to work with people from both parties. He thanked Democratic-leaning independents who voted for him and said his victory was important nationally because it meant moderate Republicans nationally were "alive and kicking."

In Arizona, a similar contest played out between conservative and moderate Republicans in a House race for a Tucson-area seat left open by retiring moderate GOP Rep. Jim Kolbe. National GOP leaders angered local Republican candidates when they jumped into the race to support moderate state Rep. Steve Huffman.

With 89.6 percent of the district's precincts reporting, conservative former state lawmaker Randy Graf, who had made his opposition to illegal immigration the center of his campaign, led Huffman 21,587 to 18,785, or 43 percent to 37.4 percent.

Party officials have expressed concerns Graf may be too conservative to beat the Democratic contender — former state legislator Gabrielle Giffords.

In the Maryland race to fill the Senate seat held by retiring Democrat Paul Sarbanes, 20-year Rep. Ben Cardin was leading Kweisi Mfume, former head of the NAACP, by a 46-to-37 percent margin with 72 percent of precincts reporting. The winner will face GOP Lt. Gov. Michael Steele, who is seeking to become the lone black Republican in the Senate.

Judges extended voting hours in Baltimore and nearby Montgomery County by one hour because of problems that delayed the opening of some polling places. Officials said some election judges did not show up on time and others had trouble getting into the facilities.

In New York, Clinton beat challenger Jonathan Tasini with more than 80 percent of the vote. She will face former Yonkers Mayor John Spencer.

Spitzer defeated Nassau County Executive Tom Suozzi with more than 80 percent of the vote. He will be heavily favored in the fall against the GOP nominee, former legislative leader John Faso.

Former federal Housing Secretary Andrew Cuomo — son of former Gov. Mario Cuomo — defeated Mark Green, the former New York City Public Advocate, to win the Democratic nomination for attorney general.

Elsewhere:

— District of Columbia voters choose City Council member Adrian M. Fenty in the mayoral primary. In heavily Democratic Washington, the primary is tantamount to the general election.

— In Vermont, Rep. Bernie Sanders won the Democratic nomination for Senate. Sanders, who plans to run as an independent, aims to win the seat of retiring Sen. James Jeffords, the Senate's lone independent. He will face the Republican nominee, businessman Richard Tarrant.