WASHINGTON — Republicans wrested Virginia from the Democrats Tuesday in a one-sided sweep of top offices, and New Jersey's unpopular Democratic Gov. Jon Corzine fought for his political life as independent voters swung behind the GOP in elections in both states. It was a troubling sign for President Barack Obama 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 was a triumph for a GOP looking to rebuild after being booted from power in national elections in 2006 and 2008. It also was a setback for the White House in a swing state that was a crucial part of Obama's electoral landslide just a year ago.

In New Jersey, the early vote count showed Republican challenger Chris Christie leading Democrat Corzine. Exit polls showed independents heavily favoring Christie.

Voters in both Virginia and New Jersey said their top concern was the economy.

Elsewhere, Maine voters weighed in on same-sex marriage in a closely watched initiative, and New York and California picked congressmen for two vacant seats. A slew of cities selected mayors, and Ohio voted on allowing casinos.

One year after Obama won the White House in an electoral landslide and Democrats expanded their majorities in Congress, much of the focus was on Virginia and New Jersey. The outcomes were sure to feed discussion about the state of the electorate, the status of the diverse coalition that sent 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.

As if on cue, Senate Democratic leader Harry Reid indicated Tuesday that Congress may not complete health care legislation this year, missing Obama's deadline on his signature issue and pushing debate into a congressional election year.

The president had personally campaigned for Deeds and Corzine, raising the stakes in low-energy off-year elections. Thus, even one Democratic loss was a blot on Obama's political standing to a certain degree and signaled 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.

Democrats had won big victories in Virginia in 2006 and 2008, and they have considered New Jersey a stronghold.

But interviews with voters leaving polling stations in both states on Tuesday were filled with reasons for Democrats to be concerned and for Republicans to be optimistic.