WASHINGTON -- Independents who swept Barack Obama to a historic 2008 victory broke big for Republicans yesterday as the GOP wrested political control from Democrats in Virginia and New Jersey, a troubling sign for the president and his party heading into an important midterm election year.

Conservative Republican Bob McDonnell's victory in the Virginia governor's race over Democrat R. Creigh Deeds and moderate Republican Chris Christie's ouster of unpopular New Jersey Gov. Jon Corzine was a double-barreled triumph for a party looking to rebuild after being booted from power in national elections in 2006 and 2008.

Elsewhere yesterday, Maine voted on whether to affirm a state law that would allow same-sex couples to wed. If supporters prevail, it would mark the first time that the electorate in any state endorsed gay marriage. But late returns showed foes of gay marriage winning.

In Ohio, voters decided to allow full-service casinos to be built in Cleveland, Columbus, Cincinnati and Toledo.

And voters chose a congressmen in the GOP-held vacant 23rd Congressional District seat in New York, where Democrat Bill Owens led in the early vote count over conservative Doug Hoffman. That race highlighted fissures in the Republican Party and illustrated hurdles the GOP could face in capitalizing on any voter discontent with Mr. Obama and Democrats next fall.

California also picked a congressman for a vacant seat and a slew of cities selected mayors, including New York, which gave Michael Bloomberg a third term.

The outcomes of Virginia and New Jersey were sure to feed discussion about the state of the electorate, the status of the diverse coalition that sent Mr. Obama to the White House and the limits of the president's influence -- on the party's base of support and on moderate current lawmakers he needs to advance his legislative priorities.

His signature issue of health care reform was dealt a blow hours before polls closed when Senate Democratic leader Harry Reid signaled that Congress may not complete health care legislation this year, missing Mr. Obama's deadline and pushing debate into a congressional election year. Democrats in swing-voting states and moderate-to-conservative districts may be less willing to back Mr. Obama on issues like health care after Virginia and New Jersey showed there are limits to how much he can protect his rank and file from fallout back home.

The president had personally campaigned for Mr. Deeds and Mr. Corzine, seeking to ensure that independents and base voters alike turned out even if he wasn't on the ballot -- and voters still rejected them. Thus, the losses were blots on Mr. Obama's political standing to a certain degree and suggested potential problems ahead as he seeks to achieve his policy goals, protect Democratic majorities in Congress and expand his party's grip on governors' seats next fall.

Interviews with voters leaving polling stations in both states were filled with reasons for Democrats to be concerned and for Republicans to be optimistic, particularly about independents -- the crown jewel of elections because they often determine outcomes.

Independents were a critical part Mr. Obama's victory in Virginia, New Jersey and across the country. But after more than a year of recession, they fled from Democrats in the two states, where the economy trumped all.

In Virginia, Mr. McDonnell won by big margins in rapidly growing, far-flung Washington, D.C., suburbs -- places like Loudoun and Prince William counties -- that Republicans historically have won but where Mr. Obama prevailed last fall by winning over independents and swing voters. Republicans swept all three statewide Virginia offices up for election: governor, lieutenant governor and attorney general.

"Bob McDonnell's victory gives Republicans tremendous momentum heading into 2010," declared Gov. Haley Barbour of Mississippi, chairman of the Republican Governors Association. "His focus on ideas and pocketbook issues will serve as a model for Republicans running next year."

Said Tim Kaine, the Democratic National Committee chairman and the term-limited Virginia governor: "We are disappointed."

In both states, the surveys also suggested the Democrats had difficulty turning out their base, including the large numbers of first-time minority and youth voters whom Mr. Obama attracted. The Virginia electorate was whiter in 2009 than it was in 2008, when blacks and Hispanics voted in droves to elect the country's first black president.

In New Jersey, Mr. Christie, a former U.S. attorney, rode a wave of voter outrage over taxes and the recession to a decisive victory despite being outspent by as much as 3 to 1. He led Mr. Corzine 49 percent to 44 percent with 80 percent of the ballots counted.

Mr. Corzine had spent most of the summer trailing Mr. Christie by 10 percentage points and more. The race tightened this fall, with a surge by third-party candidate Chris Daggett.

Mr. Christie benefited by a stronger-than-expected turnout in GOP strongholds and a feeble showing by Mr. Daggett, who Democrats had hoped would split the anti-Corzine vote. Yesterday, he captured only about 5 percent of the electorate.

No Republican has won statewide office in New Jersey in more than a decade. Exit polling showed that voters who describe themselves as independent voted 2 to 1 for Mr. Christie.

In Boston, Mayor Thomas M. Menino won an unprecedented fifth term, defeating his fellow Democrat, City Councilman Michael F. Flaherty Jr. It was the toughest re-election fight of Mr. Menino's career, but he relied on his popularity and impressive political machine to neutralize arguments that the city needed a change.

Mayor Dave Bing of Detroit, a former basketball star and founder of an auto parts supplier, won election to a full term in the financially-struggling city. The night's results may mark the city's long-awaited end to the fallout from a scandal that led to the departure of a former mayor and has sent Detroiters to the polls four times since February.

New York Mayor Bloomberg won reelection yesterday, giving him the third term he began seeking last year in campaigning for a change to the city's term-limits law.

But it was a hard-won victory. Despite an election-eve poll that showed Mr. Bloomberg comfortably ahead of Democratic Comptroller William Thompson, the result was in doubt for much of the night before Mr. Bloomberg pulled away late. With 95 percent of precincts reporting, Mr. Bloomberg led Mr. Thompson by 4 percentage points in the eight-candidate field.

The closeness of his victory is sure to raise speculation about the impact of the term-limits change and how much that served to trump Mr. Bloomberg's accomplishments in office. That subject had already dominated conversation at polling places around the city Tuesday.

"The main thing is to get Bloomberg out," said Veronique Doumbe, 52, a filmmaker from West Africa, speaking at an East Village polling place. "I'm coming from a country where the president never wants to leave. Term limits are essential for a democracy."

Even Mr. Bloomberg supporters said the change in the law gave them pause.

"I'm not crazy about the way he got himself on the ballot again, but I love the fact that he's non-political," said Vana Gierig, 48, a pianist. "I love the fact that he's creating bike paths."

Other supporters of the self-financed billionaire businessman and political independent said they hoped his business sense could help steer the city into economic recovery. They said they appreciated his even keel and business-like approach to problems among various groups.

Off-year races are often sleepy affairs, and the turnout, for the most part, appeared to be low yesterday. Few long lines were reported, even in New Jersey, the scene of the one of the day's toughest-to-call races. Voter apathy seemed to belie the more dramatic narrative that has been hoistedon yesterday's races, which political officials have described as high-stakes contests that could shape next year's congressional agenda and reveal deep divisions within a Republican party seeking a return path to power.

Washington correspondent Daniel Malloy writes the "Pittsburgh On The Potomac" blog exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.