The last five midterm elections following one party's sweep of these two contests produced mixed results. Twice, in 1993 and 2005, they contributed to a comeback the following year for the party out of power, which picked up 52 and 30 seats, respectively, in the House. After two others, 1989 and 2001, the out-of-power Democrats picked up eight and six House seats, respectively, in the subsequent midterms. And following 1997, Republicans actually had a net loss of five seats.

What's more, the two Democrats were hardly ideal candidates: Pre-election polls had Corzine's disapproval rating hovering around 55 percent, and Deeds struggled to define himself on taxes, transportation and even vis-à-vis Obama.

But one thing is clear: Without Obama on the top of the ticket, Democrats are going to have to figure out how to energize his 2008 supporters if they want to avoid more losses like these in next year's midterm elections.

Turnout of younger voters who were a mainstay of the Obama coalition was down in both states. According to the National Election Pool exit poll, in the 2008 presidential election, 17 percent of the voters in New Jersey were between 18 and 29 years, and in Virginia, that cohort made up 21 percent of voters. This year, those percentages tumbled to 9 percent in New Jersey and 10 percent in Virginia.

While some recent national polls have shown Republican Party identification at low ebb, the partisan makeup of the electorate in both Virginia and New Jersey was also more favorable to the GOP than in the presidential election.

In Virginia, the partisan composition changed notably. In the presidential election, the share of voters who identified themselves as Democrats was 39 percent, while 33 percent called themselves Republicans and 27 percent identified as independents or something else. But on Tuesday, those percentages were practically flipped: 37 percent identified themselves as Republicans, 33 percent Democrats, and 30 percent independent or something else.

In New Jersey, the partisan shifts were less dramatic. In the presidential election, 44 percent of the Garden State voters called themselves Democrats, while 41 percent did so in the governor's race. Republican identifiers edged up from 28 percent in 2008 to 31 percent on Tuesday. The percentage of those who identified as independents or something else was unchanged: 28 percent.

But Christie compensated for the partisan deficit by capturing the vote of independents, who supported him over Corzine by a 2-to-1 margin, 60 percent to 30 percent. In the presidential election, Obama won 51 percent of the independents in New Jersey, while Republican nominee John McCain took 47 percent.

Independents also rewarded the GOP standard-bearer in Virginia: Sixty-six percent cast their ballots for McDonnell, while only 33 percent backed Deeds. In 2008, Obama edged McCain among independents, 49 percent to 48 percent.

Winning this pair of off-year elections does not always translate into success in the subsequent midterm contests when much more is at stake between the two parties. But at the very least, the statehouse victories in Virginia and New Jersey will give the Republicans a boost in morale, and won't hurt their fundraising and candidate recruitment efforts either.

And some Republicans hope that the results from these off-year races will be a warning shot to moderate Democrats in Congress, or those in swing seats, that they shouldn't sign on to their leaders' and the president's sweeping agenda on health care reform and cap-and-trade energy legislation.

In Virginia, three Democratic freshmen who won competitive races in 2008 capturing a seat previously held by the GOP are emblematic of that group: Glenn Nye of the 2nd District, who represents the Norfolk-Virginia Beach area where the African-American population is more than 20 percent; Tom Perriello of the 5th District, which takes in rural portions of the south-central part of the state along with the college town of Charlottesville, which gave him huge margins; and Gerald Connolly of the 11th, who represents a district with a minority population of almost 40 percent as well as upscale Washington suburbs.

These Democrats got a significant lift in their 2008 campaigns from the surge in Democratic turnout that Obama's candidacy generated. He carried two of those congressional districts, the 2nd and the 11th. But on Tuesday, McDonnell won more than 60 percent of the vote in Nye's and Perriello's districts and took a healthy 55 percent in Connolly's (a district that Deeds carried with almost 53 percent of the vote when he ran against McDonnell for state attorney general four years ago).

Even Fairfax County, a growing Democratic bastion before this election that makes up a significant portion of Connolly's district, gave McDonnell about a 4,500-vote margin over Deeds. That's a significant turnaround from 2005, when, with almost the same number of total votes cast, Democrat Tim Kaine won Fairfax by more than 60,000 votes to take the governorship.

All three of these Democrats are on the GOP's 2010 target list, along with 14-term Rep. Rick Boucher, who represents the largely rural 9th District in the southwest corner of the state. Boucher is accustomed to distancing himself from the national party when necessary. After McDonnell rolled up more than 66 percent of the vote in Boucher's district, Republicans are likely to pressure him, and others like him, even more so.