It is still early, but ABC News projections so far show Democrats having a good night.
They have now netted three of the six seats they need to take a majority in the Senate -- and the projections so far show no Democratic Senate incumbents who stand to lose.
In the House, Democrats have gained seven of the 15 seats they need to take control.
And in gubernatorial races, projections show they have taken four seats from Republicans.
The newest results:
RHODE ISLAND: In a close Senate race, ABC News projects that Democrat Sheldon Whitehouse will defeat the Republican incumbent, Sen. Lincoln Chafee. Chafee had distanced himself from the Bush White House, and exit polls show that 62 percent of Rhode Islanders approved of his performance -- but in a heavily Democratic state, people were voting for change. Sixty-three percent of those polled said they wanted the Democrats to win control of the U.S. Senate.
OHIO: We project that Democrat Sherrod Brown will unseat incumbent Republican Sen. Mike DeWine. Exit polls show this race was largely a referendum on President Bush's leadership: Six in 10 voters there disapproved of the president's performance -- and of those, more than 85 percent voted Democratic in the Senate race.
In Ohio's gubernatorial race, Democrat Ted Strickland appears to have beaten Republican Kenneth Blackwell in an open contest. This was a governorship that had been in Republican hands.
PENNSYLVANIA: ABC News projects that Democrat Robert Casey will win over incumbent Sen. Rick Santorum, the No. 3 person in the Senate's Republican leadership. Exit polls show that Casey's win, like Brown's in Ohio, was the product of a disgruntled Pennsylvania electorate, dissatisfied over the conduct of the Iraq War.
CONNECTICUT: Sen. Joe Lieberman, running as an Independent, defeated Democratic challenger Ned Lamont -- even though Lamont had beaten him in the Democratic primary. Lieberman has vowed to vote with the Democrats in the Senate.
NEW JERSEY: We project that Democratic Sen. Robert Menandez will win over Republican challenger Thomas Kean Jr. This was a close, hard-fought campaign, and one that Democratic managers said they had to hold if they had hopes of winning a majority in the Senate.
FLORIDA: Incumbent Democratic Sen. Bill Nelson appears to have beaten Republican Katherine Harris -- the woman who, as Florida's secretary of state in 2000, presided over the tumultuous recount of votes in the presidential race between George W. Bush and Al Gore.
INDIANA: In raw vote counts -- not projections based on exit polls -- Democrats are ahead in three House seats currently held by Republicans. Meanwhile, in the Senate there, incumbent Richard Lugar is projected to beat Libertarian challenger Steve Osborn.
MARYLAND: The governor's seat changes hands here -- ABC News projects that Democrat Martin O'Malley has unseated Republican incumbent Gov. Robert Ehrlich.
In other races, where polls had not shown races to be close, incumbents so far were keeping their seats.
NEW YORK: Sen. Hillary Rodham Clinton -- the former first lady, widely touted as a contender for president in 2008 -- is projected to have won against Republican John Spencer.
MISSISSIPPI: Republican Sen. Trent Lott keeps his seat, defeating Democrat Erik Fleming.
MASSACHUSETTS: Sen. Ted Kennedy beat back a challenge from Republican Ken Chase.
MAINE: Republican incumbent Sen. Olympia Snowe appears to have kept her seat against Democrat Jean Hay Bright.
WEST VIRGINIA: Democratic Sen. Robert Byrd is projected to have beaten Republican challenger John Raese.
VERMONT: Sen. Bernard Sanders, an independent, is projected to have beaten his Republican challenger Richard Tarrant.
VIRGINIA, TENNESSEE and SOUTH CAROLINA: We project that voters in these states have passed referenda defining marriage as the union between a man and a woman.
For a full tally of the Midterm election results, check out ABC News' ELECTION SCORECARD
On the defensive, Republicans are trying to hold onto control of the House and Senate. They could take comfort from the weather. It was rainy in many battleground states, such as Pennsylvania, New Jersey, and Maryland -- typically considered a good sign for Republican candidates, since their core voters are more likely to brave the elements than the loose coalition the Democrats have traditionally built to win major races.
Democrats hope to gain 15 or more House seats -- enough to give them a majority there for the first time in 12 years. And they are counting on voters who want to send a message to President Bush, whose 40 percent midterm approval rating is worse than that of any president since Harry S. Truman in 1950.
But Democrats may have a harder time gaining the six seats that would give them the Senate. And they worried about polls that suggested some of the momentum they had just a few weeks ago may have slowed.
Some notes from Gary Langer, director of ABC News' Polling Unit:
Preliminary exit poll results indicate that nearly six in 10 voters today disapprove of the way the president is handling his job. About four in 10 approve. That's down from a 53 percent approval in 2004, and 67 percent just before the 2002 midterm election.
About four in 10 "strongly" disapprove of the president's work, more than double the number of strong approvers. Intensity of sentiment by contrast was about equal in 2004 — 33 percent strongly approved of the president's performance, 35 percent strongly disapproved. And in 2002, strong approvers dominated, quite a contrast from today.
The war in Iraq is a serious concern. In preliminary exit poll results, nearly six in 10 voters disapprove of the war, while about four in 10 approve. Approval of the war was higher -- 51 percent -- in the 2004 election. And about four in 10 now "strongly" disapprove of the war, up from 32 percent two years ago.
Related to concerns about the war in Iraq, voters today are more apt to say the country's seriously off on the wrong track than to say it's going in the right direction. The last time this view was more negative than positive was back in 1994.
The president, at least to some extent, is looking like a drag on his party this election. In preliminary exit poll results, voters by more than a 10-point margin are more apt to say they're voting to show opposition to Bush rather than to show him support. More than a third are voting to show opposition to the president. That compares to 21 percent in 1998, during the Clinton/Lewinsky scandal, and 27 percent in 1994, when the Republicans took control of Congress.
One final note:
There are 15 states with statewide races and no exit polls. In these states, we are basing calls on the actual tabulated vote. Those states are: