All won seats left open by Republican retirements.

In New Hampshire, former Gov. Jeanne Shaheen defeated Republican Sen. John Sununu in a rematch of their 2002 race, and Sen. Elizabeth Dole fell to Democrat Kay Hagan in North Carolina.

Democrats also looked for gains in the House. They defeated Republican incumbents Rep. Tom Feeney and Ric Keller in Florida, 22-year veteran Chris Shays in Connecticut and Rep. Robin Hayes in North Carolina.

At least two Democrats lost their seats. Rep. Kevin Mahoney fell after admitting to two extramarital affairs while serving his first term in Florida. In Louisiana, Democratic Rep. Don Cazayoux lost the seat he had won in a special election six months ago.

The resurgent Democrats also elected a governor in one of the nation's traditional bellwether states when Missouri Attorney General Jay Nixon won his race.

The White House was the main prize of the night on which 35 Senate seats and all 435 House seats were at stake. A dozen states elected governors, and ballots across the country were dotted with issues ranging from taxes to gay rights.

An estimated 187 million voters were registered, and in an indication of interest in the battle for the White House, 40 million or so had already voted as Election Day dawned.

Obama sought election as one of the youngest presidents, and one of the least experienced in national political affairs.

That wasn't what set the Illinois senator apart, though -- neither from his rivals nor from the other men who had served as president since the nation's founding more than two centuries ago.

A black man, he confronted a previously unbreakable barrier as he campaigned on twin themes of change and hope in uncertain times.

McCain, a prisoner of war during Vietnam, a generation older than his rival at 72, was making his second try for the White House, following his defeat in the battle for the GOP nomination in 2000.

A conservative, he stressed his maverick's streak. And although a Republican, he did what he could to separate himself from an unpopular president.

For the most part, the two presidential candidates and their running mates, Biden and Republican Gov. Sarah Palin of Alaska, spent weeks campaigning in states that went for Bush four years ago.

McCain and Obama each won contested nominations -- the Democrat outdistancing former first lady Hillary Rodham Clinton -- and promptly set out to claim the mantle of change.

Obama won Colorado, Nevada, California, Hawaii, Oregon, Washington, Florida, Virginia, New Mexico, Iowa, Ohio, Wisconsin, Michigan, New York, Rhode Island, Minnesota, Pennsylvania, New Hampshire, Vermont, Connecticut, Delaware, Illinois, Maine, Massachusetts, Maryland and New Jersey, as well as the District of Columbia.

McCain had Nebraska, Idaho, Mississippi, Texas, West Virginia, Utah, Arkansas, Kansas, Kentucky, Tennessee, Oklahoma, Wyoming, Alabama, South Carolina, Louisiana, South Dakota and North Dakota.