Tuesday’s legislative elections in Virginia appeared likely to add more evidence — as if national Democrats needed it — that the terrain of the political map will be significantly more rugged for President Obama next year.

It is difficult to draw a bright trend line from an election in which fewer than one-third of those registered voted. When turnout is as light as it was on Tuesday, those who do show up tend to be the most dogged partisans.

But analysts and political strategists of both parties said the expected Republican gains — even if less than was expected — underscored the need for the president to reinvigorate his supporters and close what is becoming known as the “enthusiasm gap” between the two parties.

“The enthusiasm gap has been completely reversed in the state. Republicans have it. Democrats don’t,” said political scientist Bob Holsworth, a former professor at Virginia Commonwealth University who now runs a Web site called Virginia Tomorrow.

In 2008, Obama’s seven-point victory in Virginia marked the first time that any Democratic candidate had carried the state since Lyndon B. Johnson’s landslide national victory in 1964. Duplicating that feat in 2012 would make his reelection significantly easier.

The political tide, however, has been running the other way — starting with the 2009 election of Republican Gov. Bob McDonnell and continuing with GOP victories in last year’s midterm elections.

“Independents specifically have rejected the Obama agenda, and they are fully supportive of the McDonnell agenda,” said Phil Cox, who managed the governor’s campaign and is now executive director of the Republican Governors Association.

Meanwhile, the energy of the tea party movement has ginned up Republican enthusiasm in Virginia, as have conservative outside groups.

Tim Phillips, a veteran Virginia operative who is president of the tea party-aligned Americans for Prosperity, said his organization spent $300,000 in Virginia. Much of that money was aimed at drawing a connection between local contests and the anger that conservatives feel toward the president.

Particularly in Northern Virginia, Phillips said, polling shows “the vast majority of people really don’t know their state legislators.”

Obama’s campaign has continued to nurture his operation in Virginia. In the seven months since the president officially announced his bid for a second term, the campaign estimates that it has held 1,600 events — phone banks, house parties, voter registration drives and the like. And the president himself has been a presence in the state, most recently with a two-day swing last month to promote his jobs plan.

That kind of effort, however, doesn’t necessarily pay off for local candidates in an election in which the president himself is not on the ballot, said Mark J. Rozell, a professor of public policy at George Mason University.

“If anything,” he added, “the president is a negative right now for Democrats running in Virginia.”

Democrats in a number of tight races resisted their opponents’ efforts to tie them to the president. House Minority Leader Ward L. Armstrong found himself the target of one such ad by his opponent, Del. Charles D. Poindexter.

So Armstrong put up his own spot, in which he responded: “That’s a stretch, Charles. I’m pro-life, pro-gun and I always put Virginia first.” Armstrong was trailing Poindexter with 95 percent of the votes counted.

Bolstering the Democrats’ confidence for next year, however, is the expectation that the shape and the size of the electorate will be very different, in Virginia as elsewhere.

“Turnout is everything,” said Rep. Gerald E. Connolly, a Northern Virginia Democrat. He noted that presidential election years tend to bring out three times as many people as voted in Virginia on Tuesday, including large blocs of minority voters who tend to sit out off-year contests.

“Those are very different electorates,” Connolly said late Tuesday, “no matter what happens tonight.”

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